*Article* **The Agricultural Cooperative as an Instrument for Economic Development: An Approach from Spanish Investors' Preferences through a Choice Experiment**

**Ángel Sabino Mirón-Sanguino and Carlos Díaz-Caro \***

Department of Finance and Accountability, University of Extremadura, 30100 Caceres, Spain; asmiron@unex.es **\*** Correspondence: carlosdc@unex.es

**Abstract:** The cooperative is one of the most important forms of business in the agricultural sector, due to its special characteristics for small farmers and livestock producers in order to gain access to greater comparative advantages. In addition, cooperatives are a driving force in the social economy, which means that investment in agricultural cooperatives can be seen as a sustainable investment. The aim of this paper is to analyse the preferences of investors in agricultural company cooperatives, looking in depth at the role of the cooperative as a business form. In order to achieve this objective, the choice experiment methodology was applied by carrying out a questionnaire to a total of 282 investors. Latent class models were also used to identify possible groups of investors. Two classes of investors have been identified based on their preferences: owners (return seeking) and workers (risk averse).

**Keywords:** cooperatives; choice experiment; ownership; agronomy

**Citation:** Mirón-Sanguino, Á.S.; Díaz-Caro, C. The Agricultural Cooperative as an Instrument for Economic Development: An Approach from Spanish Investors' Preferences through a Choice Experiment. *Agronomy* **2022**, *12*, 560. https://doi.org/10.3390/ agronomy12030560

Academic Editors: Riccardo Testa, Giuseppina Migliore, Giorgio Schifani and József Tóth

Received: 11 January 2022 Accepted: 21 February 2022 Published: 24 February 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

### **1. Introduction**

The cooperative in the agricultural sector has several relevant factors to justify its existence and development. In particular, the literature on economic organization shows the ability of cooperatives to reduce transaction costs and their capacity to develop countervailing power [1]. Thus, the recognition of the efficiency of agricultural organization is fundamentally determined by two factors, the efficiency of the division of labour and the efficiency of control activity, of which the second reason is more relevant. In this sense, cooperatives have a key role to contribute to the efficiency of the control activity, resulting in a form of continuity of the family farms that characterize the agricultural organization.

The cooperative company can be defined as the association of members (workers, producers, clients, etc.) to achieve an economic and social objective, taking decisions in a democratic manner, in comparison to the definition of other types of companies that are usually set up with independent shareholders and management. In the cooperative company, ownership and control of the company is usually shared, which leads to a coordination of objectives and elimination of opposing interest groups, as is the case in other types of companies. In turn, cooperative investment is affected by financial constraints in a relevant way [2], which highlights the importance of knowing how it is possible to invest in this type of financial product.

The cooperative as a legal form in Spain is developed in Law 27/1999 on Cooperatives (BOE, 1999), which specifies that there are basically two types of members: those members who carry out the corporate activity and collaborating members who do not necessarily have to carry out this activity. However, the collaborating partners have limitations in terms of both the percentage of capital and voting rights. In this sense, decision-making, management and control end up residing with the members who participate in the cooperative.

The legal form of a cooperative has a few economic and social advantages for society. Specifically, this type of enterprise contributes to the financing, maintenance, and stability of job creation [3]. It also allows the incorporation of women into the labor market, creating opportunities and meeting different needs in rural areas, contributing to more sustainable development [4]. Furthermore, investment in agricultural cooperatives is of vital importance for the sustainability of the agricultural system [5].

Currently, there are some 3699 agricultural cooperative companies in Spain, with a turnover of 30,556 million euros in 2019, representing 68% of final agricultural production. The total number of members amounts to more than 1 million, with a contribution to employment of around 112,000 employees. This shows the economic importance of the agricultural cooperative in Spain [6]. Cooperatives can be classified as first grade cooperatives if their members are individuals and second grade cooperatives if their members are, in turn, other cooperatives. The majority of cooperatives are located in first and second grade cooperatives, accounting for a total of 91%, with most of them concentrated in Andalusia, Castilla la Mancha and Castilla y León.

On the other hand, the social economy has shown great growth, especially in the area of the entrepreneurial business sector [7]. In this field, the agricultural cooperative is one of the key instruments in the development of this type of economy. Furthermore, cooperatives promote and foster the achievement of several Sustainable Development Goals, including poverty reduction, food security and good nutrition, sustainable energy, promotion of stable and peaceful societies, etc., ("Cooperativas hacia 2030", 2018; Internacional, 2015).

In this sense, investment in this type of company provides solutions to the current capitalist market, as they contribute not only economically but also by incorporating social and environmental aspects that are not usually addressed by other types of companies [8]. Therefore, localizing investment in cooperatives involves allocating resources towards a more socially responsible investment policy than the traditional one that only pursues economic profit. For all these reasons, the cooperative form in the agricultural sector can be considered as an instrument for the sustainability of the system.

The literature provides a significant number of papers on cooperatives. From works that analyse the control rights in cooperatives determined by the types of members that configure it [9,10], the investment behaviour of members [5,6,11–13], cooperative social inclusion [14], cooperative social responsibility and the cooperative [15], to efficiency and productivity [16,17].

However, the literature has not paid much attention to the willingness of non-member investors to invest in agricultural cooperatives. Only the work carried out by Alho, 2017, which analyses the investment preferences in agricultural cooperatives for a set of investors in Finland, stands out. Its main findings show that there is a willingness to invest in agricultural cooperative investment instruments and that a significant part of the sample is particularly interested in the attribute related to voting rights. Knowing what the investment preferences are in this type of instrument is useful to develop possible measures to increase the attractiveness of the investment for investors.

In this regard, the aim of this paper is to analyse the preferences of investors to invest in agricultural cooperatives and to analyse how various attributes influence their decision. The importance of raising funds for the agricultural cooperative is key to the sustainable development of the agricultural economy, in addition to the potential rural development that this type of enterprise brings. The importance of knowing the preferences of investors is relevant for planning investment projects and generating legal structures to attract investment to cooperatives. In addition, it also explores whether preferences are heterogeneous, trying to identify different groups of investors according to their preferences and characteristics. To achieve the proposed objective, a total of 282 investors were interviewed. A choice experiment was used to analyse the preferences and obtain the most important attributes. Additionally, latent classes were applied to identify homogeneous groups.

### **2. Material and Methods**

#### *2.1. Database*

The database to carry out the objective of this work has been obtained from a questionnaire conducted on a sample of Spanish investors by means of random sampling. The final sample is made out of 282 individuals who have invested in some financial product and, therefore, can be considered investors (both investors and working members). The questionnaire is composed of information on the socio-economic environment as well as variables on risk perception and sustainability. The main descriptive statistics of the sample are shown in Table 1.

**Table 1.** Main descriptive statistics of the sample.


The sample obtained was collected by means of simple random sampling without being able to count on an objective representativeness given that the characteristics of Spanish investors are unknown. We do not know the target population since no data are available on the investor population in Spain. The status of an investor has been determined by asking whether he/she has ever invested in financial products.

The questionnaire was prepared using Google Forms, as this type of online tool is increasingly used in research due to its advantages in terms of flexibility, speed of data collection and lower cost than traditional surveys [18–20].

#### *2.2. Choice Experiment*

The paper is based on the choice experiment conducted by [16] but adapting the attributes and levels to the Spanish regulations. Choice experiments have been widely used in the field of economics to analyse preferences [21–24]. These experiments are based on the idea that a product can be decomposed as the sum of several attributes that characterise it. Specifically, the following attributes have been incorporated: the voting rights of the shareholder, the profit entitlement, the share price and the expected return and risk. The selection of attributes and levels has been based on the literature review and the current legal configuration of the cooperative in Spain. All the attributes, as well as the different levels, are listed in Table 2.

Voting rights refer to the configuration of voting rights held by the shareholder or owner/investor of the cooperative. Profit entitlement is the form in which the shareholder/owner/investor's investment is remunerated. Capital price to the way in which the price is configured, whether in a secondary market or not. Finally, the level of risk and profitability of the investment is included.

Considering the four attributes mentioned above, with the different levels in each case, a total of 6,480 (3 × 3 × 3 × 3 = 81) possible combinations of plausible scenarios can be established. Given the large number of resulting comparisons, for economic and time reasons it was decided to apply a factorial design. This procedure resulted in a total number of 16 alternatives, which meant that each respondent was faced with a set of eight choices. This type of design practice is frequently used in choice experimentation [25]. Figure 1 shows an example of a choice set.


**Table 2.** Attributes and levels of the Choice Set.


**Figure 1.** Example Choice Set.

### *2.3. Econometric Model*

The model used to analyse investors' preferences for participation in agricultural cooperatives was the conditional logit model, and a latent class model was also implemented in order to study unobservable heterogeneity and different types of investors based on the response of the responses to the valuation.

These models, which are a derivative of random utility models [26], assume that the utility function of each individual is the sum of two terms, a deterministic part that can be described as a function of the factors that influence individuals' utility and a random, unobserved part that is considered stochastic. So, following [27] we can assume a sample of N individuals with a choice between J alternatives on T occasions, where the utility of an individual *n* derived from the choice of alternative j on occasion t is as follows:

$$
\mathcal{U}\_{n\bar{\jmath}t} = \mathcal{S}\_n' \mathfrak{x}\_{n\bar{\jmath}t} + \mathfrak{e}\_{n\bar{\jmath}t} \tag{1}
$$

where *β <sup>n</sup>* is the vector of individual-specific coefficients, *xnjt* is the vector of observable attributes of individual *n* and alternative *j* at choice occasion *t*, and *εnjt* is the random term that we assume to be an independently and identically distributed extreme value. Therefore, the probability of respondent *n* choosing alternative I at choice t is given by the following expression:

$$L\_{\rm init}(\beta\_n) = \frac{e \exp(\beta\_n' \mathbf{x}\_{\rm init})}{\sum\_{j=1}^{J} e \exp(\beta\_n' \mathbf{x}\_{\rm inj})} \tag{2}$$

Expression [2] is the conditional logit formula [26] In this paper we will use the simulation approach [28,29] where the log likelihood is given by equation [3]:

$$SLL(\theta) = \sum\_{n=1}^{N} \ln \left\{ \frac{1}{R} \sum\_{r=1}^{R} S\_n(\beta') \right\} \tag{3}$$

where *R* is the number of repetitions and *Hnq* is the rth draw from *f* (*θ*).

On the other hand, in order to identify unobservable heterogeneity and groups, latent classes are applied, which are estimated from:

$$SLL(\theta) = \sum\_{n=1}^{N} \ln \left\{ \sum\_{q=1}^{Q} H\_{nq} \prod\_{t=1R}^{T} \prod\_{t=1R}^{J} \left[ \frac{\exp \left( \mathbf{x}\_{njt}^{\prime} \beta\_{n}^{r} \right)}{\sum\_{j=1}^{I} \exp \left( \mathbf{x}\_{njt}^{\prime} \beta\_{n}^{r} \right)} \right]^{y\_{njt}} \right\} \tag{4}$$

where *Hnq* is the probability of membership in a given class and is obtained from:

$$H\_{n\eta} = \frac{\exp\left(z\_n^t \gamma\_\eta\right)}{\sum\_{\eta=1}^Q \exp\left(z\_n^t \gamma\_\eta\right)}\tag{5}$$

Therefore, the functional form of the *Unjt* derived from individual *n* for alternative *j* in choice set *t* can be defined as follows:

$$\begin{split} \|I\_{\text{njt}} \| \quad &= \beta\_0 ASC + \beta\_1 SIN\_{\text{njt}} + \beta\_2 PROD\_{\text{njt}} + \beta\_3 DIDV\_{\text{njt}} + \beta\_4 FIA\_{\text{njt}} + \beta\_5 SECIIND\_{\text{njt}} + \beta\_6 NOMINAL\_{\text{njt}} \\ &\quad + \beta\_7 HIGH\_{\text{njt}} + \beta\_8 MEDIIL\_{\text{njt}} + \varepsilon\_{\text{njt}} \end{split} \tag{6}$$

The ASC (alternative specific constant) is defined as the alternative that represents the third option in each comparison, i.e., the alternative of not choosing any investment. The following values have been taken as base values (reference values): for voting rights, owner's voting rights (PROP); for profit entitlement, mixed remuneration; for capital price APRECIA, and finally for profitability and risk LOW.

**3. Results**

The results obtained after applying the methodology proposed above to the sample obtained are shown below. Specifically, Table 3 shows the results of the logit model for the full sample. A positive (negative) sign for a coefficient indicates that it increases (decreases) the probability of choosing the investment in agriculture cooperative alternative.


**Table 3.** Results of the choice experiment.

The results show that the option of not investing in any of the proposed options has a negative utility given the negative and statistically significant coefficient of ASC. On the other hand, the fact that the investment in agriculture cooperative has a dividend is the only parameter that has a positive utility, although it is not statistically significant. The rest of the parameters have a coefficient of negative utility. However, it should be noted that the coefficients for voting for producers and a fixed remuneration are not statistically significant.

This shows that investors have a strong preference for the coefficients used as a baseline in the logit regression for the investment in agriculture cooperative, an investment set up in which voting rights are given to the owners, with a mixed payout consisting of a fixed part and a dividend, additional appreciation to the nominal value of the capital in its return, and relatively low levels of return and risk.

In terms of the level of importance of each attribute, which is determined by the value of Z, it can be seen that the ASC comes first, the quotation parameters second, the corresponding profitability in percentage terms third, followed by the cooperative's control and voting rights, and finally, the form of owner remuneration.

Next, to deal with heterogeneity, we proceed to estimate latent classes as shown in the methodology section. The models have been estimated with different number of latent classes and subsequently the model fit parameter has been obtained. Table 4 shows the traditional statistical tools to select the optimal number of classes according to the model fit.


**Table 4.** Statistical parameters for fit the class number.

Table 4 shows the AIC, CAIC and BIC statistics, which show a better fit the lower the number obtained. In this sense, it can be seen that for both statistics the optimal model to estimate would be the one composed of two latent classes.

Table 5 shows the results of the choice experiment with latent classes.


**Table 5.** Results of the choice experiment with latent classes.

The ASC coefficient is negative and statistically significant in both classes. The first class consists of 27.5% while the second class comprises 72.5% of the respondents. The first class has statistically significant and positive coefficients for medium and high return and risk, while the coefficients are negative and statistically significant for no voting rights, secondary market listing and a return of nominal value, i.e., they prefer to have a vote as

owners and a return of capital taking into account the nominal value plus a premium with high levels of return and risk. This type of class can be referred to as return seeking or ownership.

In the case of the second class, it can be observed that the coefficient of owners' voting rights is positive and statistically significant together with the secondary market price. However, both fixed and dividend remuneration, no voting rights and nominal return have a statistically insignificant coefficient. On the other hand, high and medium returns and risk report statistically significant but negative coefficients. In this sense, this majority group could be referred to as risk averse or working.

### **4. Discussion**

The aim of this paper is to analyse the preferences of Spanish investors regarding investment in agriculture cooperative instruments in agricultural cooperatives and to determine which factors are most relevant. The cooperative in the agricultural market in Spain plays a fundamental role for the development of the sector in general and in particular for certain areas that otherwise would not find a way to develop and obtain economic growth, especially those located in non-urban centres.

The overall results show a trend towards an investment in an agriculture cooperative model that is characterised by a demand for instruments that have rights for owners to vote for control of the cooperative, with relatively low levels of return and risk, more in line with traditional investments in agriculture cooperative and that do not have high volatilities [29,30]. This result is in line with that obtained for a similar analysis in the Finnish case [13], although it differs in the profitability attribute, where the latter has a higher tendency towards profitability and high levels of risk.

Control of the cooperative is one of the most relevant attributes, apart from the return of capital, which shows that the organisation and governance of the cooperative is an attribute that is very important in this type of enterprise, as shown by various studies [31–33]. One possible explanation for this result lies in the fact that this type of instrument places greater emphasis on the investor's involvement in the management and growth of the company than on the pure holding of the stake.

The fact that the ASC has a negative result shows a certain rejection of this type of instrument, unlike the results obtained for the Finnish case [13]. However, this result can be explained by the cultural aspect of both countries, with Spain being a country that is more reserved when it comes to non-traditional investments, and investment in cooperatives may fall outside what is traditionally considered a traditional investment.

Moreover, an investment in cooperatives can be seen as an illiquid product (as most of them are not listed), as evidenced by the high importance given by investors to listing as an attribute. This fact could lead to higher levels of trading of the shares, although it is also true that this would probably lead to greater volatility marked by the prices at which they are listed.

The estimation by latent classes has made it possible to obtain two types of investors. On the one hand, those referred to as owners or seeking return and those that we can call risk adverse or working. The identification of two groups is slightly lower than that obtained by [13], which manages to separate those investors who are owners from those seeking returns, but the types of investors can be considered similar, although it is true that the probability of belonging or class size is very different. Again, the explanation for this lies in the cultural factor as has been shown internationally with other investment products.

Preferences for investing in cooperative instruments clearly show a higher probability and size group, which are workers or risk-averse, which shows that this type of investment in agriculture cooperative is more focused on workers who own the enterprise and want at least effective control or representation in the enterprise, rather than high profitability. This group could become the actual owners of the cooperatives and channels a way to avoid the financial constraints that agricultural cooperatives face in terms of possible financing [2].

The results of class 2 are in the opposite direction to those obtained by studies that analyse investment in agricultural cooperatives from the point of view of the owner in countries such as Greece or China [5,33,34], although this approach is different, it can serve as an approximation and comparison to the results obtained in this paper. However, regional differences in these countries must be taken into consideration. In these studies, profitability is one of the determining factors, but also the future strategies of the cooperative, as well as the governance of the cooperative, the latter of which seems to be in line with the results obtained in this study.

### **5. Conclusions**

The aim of this paper has been to analyse investors' preferences for investment products located in agricultural cooperatives. Agricultural cooperatives play a fundamental role in the development and growth of the agricultural sector. Therefore, it is essential to know which are the most demanded preferences and characteristics in order to be able to organise this instrument in an adequate way. A segmentation of investors by latent classes has also been carried out in order to identify investors with their own independent characteristics.

The main results have shown that profitability is one of the determining factors in investment in cooperatives, although control of the cooperative and, therefore, voting rights is a factor that is very present when investing in this type of instrument. The most relevant factor, apart from the ASC, is the price, due to the possible lack of liquidity of the instrument. In this sense, an organised market for investment in cooperatives could lead to a greater increase in this type of product, as its investment would be more liquid and it would be easier to invest.

The latent classes have made it possible to identify two types of investors: those who can be described as owners who expect a high return on their investment and who have turned out to be the minority group and, on the other hand, a group of investors who are more risk-averse and prefer greater control by the producers, who have been described as risk averse or working, this group being the most numerous or probable in the estimation of the latent classes.

The identification of these two groups clearly shows that this type of instrument is aimed at investors who wish to become involved in the business in which the agricultural cooperative operates and, therefore, influence its management. This seems to indicate that two types of shareholdings could be articulated for the ownership of cooperatives, as is currently regulated in Spain. The results obtained are in line with those obtained in the case of Finnish investors.

The research carried out has several implications for the stakeholders. First of all, for the managers of the cooperative to know what the preferences of the investors are in the cooperative and to act accordingly. For governments, they can take these preferences into account in carrying out future reforms. Finally, for investors, knowledge of their preferences can show those projects that may be more attractive for attracting capital and, therefore, for business success. In this way, such projects can have more resources and the investor can locate its resources there.

This paper presents future lines of research to be developed, which at the same time can be assumed as limitations of the study. Firstly, it would be interesting to know the difference between those who are already owners of agricultural cooperatives and those who are not and could become so. Secondly, an interesting aspect to develop would be to find out the main motivations that investors have for allocating their funds in these instruments, beyond the characteristics or attributes mentioned above, as observed in various studies.

**Author Contributions:** Conceptualization, Á.S.M.-S. and C.D.-C.; methodology, Á.S.M.-S. and C.D.- C.; software, Á.S.M.-S. and C.D.-C.; validation, Á.S.M.-S. and C.D.-C.; formal analysis, Á.S.M.-S. and C.D.-C.; investigation, Á.S.M.-S. and C.D.-C.; resources, Á.S.M.-S. and C.D.-C.; data curation, Á.S.M.-S. and C.D.-C.; writing—original draft preparation Á.S.M.-S. and C.D.-C.; writing—review and editing, Á.S.M.-S. and C.D.-C.; visualization, Á.S.M.-S. and C.D.-C.; supervision, Á.S.M.-S. and C.D.-C.; project administration Á.S.M.-S. and C.D.-C. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors would like to acknowledge the support and funding provided by the Junta de Extremadura and FEDER Funds through Grants GR, which made this research and its translation possible.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data available upon request.

**Acknowledgments:** The authors would like to acknowledge the support and funding provided by the Junta de Extremadura and FEDER Funds through Grants GR, which made this research and its translation possible.

**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

### **References**


**Patrycja Wojciechowska \* and Karolina Wiszumirska**

Department of Industrial Products and Packaging Quality, Pozna ´n University of Economics and Business, Al. Niepodległo´sci 10, 61-875 Poznan, Poland; karolina.wiszumirska@ue.poznan.pl

**\*** Correspondence: patrycja.wojciechowska@ue.poznan.pl

**Abstract:** The purpose of this study was to widen the knowledge about the recycling behaviour of consumers in order to understand their motivations related to the separate collection of household waste. This work encompasses a segmentation analysis revealing discrepancies between the respondents, who were profiled into three clusters: *Engaged in green*, characterised by high values of pro-environmental attitudes; *Indolent adopters*, described by respondents revealing moderate attitudes towards sorting waste; and *Ecological objectors*, who do not appreciate the benefits of recycling. The results showed that regardless of the cluster type, the level of actual knowledge about segregation rules was similar and insufficient, which hinders the correct sorting of household waste. It was also found that special attention should be paid to the quality of the information provided by FMCG packaging. Our study highlighted the need for a mandatory, precise, and coherent system of packaging labelling in order to promote pro-environmental attitudes and enhance the effectiveness of recycling.

**Keywords:** sustainable communication; recycling behaviour; consumer; packaging; labelling; segmentation; quality

### **1. Introduction**

Global pollution has become one of the most important environmental issues. This problem affects not only emerging economies, where it is the most visible due to the lack of effective waste collection systems, but it is also an urgent issue in developed countries. According to World Bank data, food and green waste, as well as paper and plastics, represent major waste streams. Since the latter ones are valuable secondary resources, recycling should be a preferred treatment operation applied for waste management [1]. In the European Union (EU-28) during the period of 2004–2018, the quantity of waste recycled increased from 45.9% (870 million tonnes) in 2004 to 54.6% (1184 million tonnes) in 2018, while the quantity of waste subjected to disposal decreased from 54.1% (1027 million tonnes) to 45.4% (984 million tonnes), respectively. In 2018, 37.9% of the total treated waste was recycled, 10.7% was backfilled, and 6.0% was treated using energy recovery. Among the remaining 45.4% of the total quantity, 38.4% was landfilled, 0.7% incinerated without energy recovery and 6.3% disposed of otherwise [2]. According to Eurostat data [2], there are significant differences among the EU Member States regarding various treatment methods. In 2019, the highest values of recycling rates of municipal waste were denoted for Germany (66.7%), Slovenia (59.2%), Austria (58.2%), the Netherlands (56.9%), Belgium (54.7%), Denmark (51.5%), and Italy (51.3%), while in the remaining countries the values were below 50% [3]. However, taking into account the increasing amount of municipal waste generated in the European Union (EU), recycling rates are still not sufficient. Therefore, waste management is one of the key elements of the European Union's environmental policy, the EU's legal framework, and a crucial part of an action plan regarding the transition to a circular economy. As a result, the amended Waste Framework Directive introduces ambitious targets for re-use and recycling rates defining the amounts which shall be increased to a minimum of 55%, 60%, and 65% by weight by 2025, 2030, and 2035,

**Citation:** Wojciechowska, P.; Wiszumirska, K. Sustainable Communication in the B2C Market—The Impact of Packaging. *Sustainability* **2022**, *14*, 2824. https:// doi.org/10.3390/su14052824

Academic Editors: Riccardo Testa, Józseph Tóth, Giuseppina Migliore and Giorgio Schifani

Received: 1 February 2022 Accepted: 24 February 2022 Published: 28 February 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

respectively [4]. A recommended way for the Member States to reach these undoubtedly challenging sustainability goals is the development of implantation plans (roadmaps) on a national level. In Poland, an appropriate document prepared by the Interdepartmental Circular Economy Group was approved by the Council of Ministers in September 2019 [5]. The Polish Roadmap focuses on several key areas such as sustainable industrial production and sustainable consumption, secondary raw materials and waste management, as well as innovation and investments. It also reflects recent changes in Polish rules of law since the implementation of the Waste Framework Directive induced several legislative amendments and had a considerable impact on the waste management system in Poland. Current regulations in this area are based on the European waste management hierarchy, strictly coherent with the circular economy model. Within the established five-step "waste hierarchy", prevention is the most preferred method, followed by preparing for re-use, recycling, and recovery, while disposal should be the last option [4]. The Polish waste collection and management system has been established stepwise since 2016 [6]. In order to comply with European Union regulations, it is based on five fractions with assigned colours: blue (paper), yellow (plastic and metal), green (glass), brown (biowaste), black (mixed waste). Since September 2019, selective waste collection in Poland is mandatory. However, despite the obligation to handle waste in a particular way, the recycling rates are still insufficient in comparison with other European countries [7,8]. In 2020, in the EU, 505 kg of municipal waste were generated per capita and 48% was recycled (including composting), while in Poland the corresponding values were 346 kg and 39%, respectively [9,10]. Furthermore, with the adoption of the actual recycling targets for the EU, this issue is even more crucial. According to the decree of the Minister for the Climate and Environment of 19 December 2021 on the annual recycling rates of packaging waste [11], the values of 30% for plastic, 51% for aluminium, 55% for ferrous metals, 66% for paper and cardboard, 62% for glass, and 19% for wood are expected to be achieved in 2022. Other increased recycling targets set for 2029, are: 54%, 59%, 78%, 83%, 74%, and 29%, respectively, to the above-mentioned fractions. Selective collection is still a challenging task for Polish consumers, although the situation is slowly changing. In 2019, only 55% of Poles declared that they segregate waste into five fractions, while in 2020 this amount increased to 77% [12,13]. Nevertheless, their actual knowledge about selective waste collection rules is on an unsatisfactory level. According to the data gathered by ARC Rynek i Opinie, only 15% of the respondents answered correctly on three questions related to the disposal of paper tissue, the wrapping for a cube of butter, and a carton package for juice [14]. One of the reasons is the lack of environmental awareness and knowledge about waste management rules combined with inaccurate information placed on the packaging, which does not refer directly to a particular fraction. Recent studies related to these issues, however few, also indicate the importance of other socio-economic aspects determining the engagement of Poles in a separate collection of waste [12–16]. Among them, the recycling behaviour of Polish consumers and their attitudes to eco-labelling in relation to waste management are of importance, pointing out a crucial role of packaging as a sustainable communication tool [17].

Packaging, from the legal regulation's perspective [18–22] and the functions performed [23–25], is a carrier of a lot of information, signs, and symbols. Displayed altogether, they might be counterproductive. The provided information is not only related to the need to ensure product and consumer safety but also necessary from the marketing point of view. It also has a direct impact on the multi-sensory customer experience at different stages of interaction with the packaging [26–32]. Communication through packaging helps build brand awareness and distinguishes the company from its competitors [28].

Packaging can be considered in its physical dimension, focusing mainly on material and constructional issues, but also in its functional dimension, which consists of elements determining its purchase-consumption nature. Purchase packaging affects the consumer at the time of buying, while consumption packaging has a greater impact at the time of use [33,34]. Packaging as an information carrier is the starting point for the further analysis of the presented research.

Various research points out that consumers, unfortunately, do not receive appropriate and understandable information, which results in confusion or indifference [35–37]. The informative function of packaging refers to the provision and uninterrupted transmission of relevant data to all participants, both in logistics chains and to individual consumers. In addition to the traditional descriptive form, information can be conveyed by pictograms, signs, and graphic symbols, which theoretically accelerate the identification of content and facilitate the understanding of the message. Data presented in graphic form (drawing, photograph, sign, pictogram) are often universal and accessible regardless of the language level of the recipient. It should be noted that the information value of packaging, determined by the obligatory code and the optional code, is an important component of its communication value. The correct choice of signs and codes forming the visual layer of packaging affects the correct perception of the product and, consequently, purchasing decisions. An excess of information or its inappropriate placement on packaging may cause information noise and the wrong perception of product features [38–40].

The information value of packaging plays also a crucial role in shaping the recycling behaviour of consumers, therefore proactive efforts are globally being made by researchers to improve the knowledge in this area [41–45]. The results of several works highlight the potential of packaging as an initiator of waste-sorting activity and indicate its impact on recycling effectiveness. However, it should be noted that the national perspective differs due to the various policies, segregation rules, and waste management systems existing in analysed countries. Nevertheless, good practices and success stories may be shared between other regions and provide the basis for a broad discussion in order to support the environmental attitudes and activities of consumers.

The aim of this study is to widen the knowledge about the recycling behaviour of consumers in order to understand the motivation of Poles related to the separate collection of waste. This paper encompasses segmentation studies based on attitudes towards recycling. It gives an insight into the environmental awareness and actual knowledge of Polish consumers related to selective waste management according to the legal requirements in Poland. Finally, it is also an attempt to provide information about factors important for consumers, which can stimulate the effective separation of waste with a particular emphasis on the information-related function of FMCG packaging.

### **2. Materials and Methods**

### *2.1. Sample and Data Collection*

The study was conducted using a computer-assisted web interview (CAWI) in January and February 2021 on a representative sample of adult Poles (N = 1029) in terms of gender, age, and education, according to Social Diagnosis reflecting the population of Polish consumers being active internet users. The study was carried out using the Market and Opinion Research Agency "SW Research" panel of respondents. The socio-demographic characteristics of the participants involved in the survey are presented in Table 1.

### *2.2. Questionnaire*

The study was based on a specially designed questionnaire which consisted of six parts. The first part included 8 statements concerning consumers' attitudes towards recycling scored on a 5-point Likert scale enabling respondents to specify their level of agreement: (1) strongly disagree, (2) disagree, (3) neither agree nor disagree, (4) agree, (5) strongly agree. The second part contained 4 statements describing the respondents' experiences and attitudes regarding the selective collection. The third part included a set of 7 statements regarding the practical information about the selective collection of household waste which was scored on a 5-point Likert scale in order to verify the importance of examined factors from consumers' perspective. The fourth part explored the level of awareness of the respondents regarding the selective collection of household waste. In this part, the actual knowledge was verified using a set of statements describing the separative waste management rules in relation to the six popular types of waste. The respondents

could choose the answer between true or false. The fifth part investigated the potential of packaging innovations regarding extended information about the product and packaging's characteristics. The last part included questions regarding the socio-demographic data of the respondents, such as gender, age, education level, and place of residence.


**Table 1.** Socio-demographic characteristics of the participants.

### *2.3. Cluster Analysis—Understanding Consumer Recycling Behaviour*

A cluster analysis was applied to segment Polish consumers according to their attitudes towards selective waste sorting. Segmentation study allows us to classify respondents in groups and to show the similarities and differences between them in relation to attitudinal variables. The cluster analysis was used to give an insight into the motivations of respondents regarding their environmental awareness, values, and social norms as well as their level of knowledge. It may be noted that several studies were published concerning the environmental awareness and recycling behaviour of Poles [12–16,46,47]; however, only limited data were available regarding the profiling of Polish consumers [15]. The results showed important discrepancies between respondents indicating the need for tailored communication and marketing activities that should be undertaken in order to promote pro-environmental attitudes. The reported data also revealed a large information gap concerning selective waste management and its negative impact on the effectiveness of recycling. Therefore, the present study is aimed at the identification of the segments of Polish consumers in terms of their recycling behaviour in order to widen the knowledge about factors that may stimulate and promote selective waste collection. The role of packaging as a communication tool providing extended information was also explored.

In the scientific literature, two main approaches are applied in a cluster analysis [41]. One is based on socio-demographic criteria and another on psychographic and behavioural criteria. The theory of reasoned action (TRA) [48] and the theory of planned behaviour (TBP) [49], revealing the relationship between attitudes and behaviours, were successfully implemented for investigations regarding recycling, consumers' choices concerning sustainable packaging, and green consumer behaviour [50]. The TBP is a conceptual extension of the theory of reasoned action (TRA) [51], which regards a consumer's behaviour as influenced by behavioural intention. TBP assumes a rational basis for consumers' behaviour, which is influenced by three variables: attitude towards the behaviour [51], subjective norms (the perception of the pressure of others' opinions), and perceived behavioural control (the person's perception of their own ability to perform a behaviour) [50,52]. An interesting approach regarding the understanding of consumer recycling behaviour was proposed by Park and Ha [53]. They showed that recycling intention is determined both by

attitudes toward recycling and by perceived behavioural control from TPB, as well as by personal norms from the norm action model (NAM, Shwartz 1997 [54]). They suggested that subjective norms indirectly influence recycling intention, having an impact through attitude, personal norms, and perceived behavioural control [53]. According to NAM, personal norms refer to the individual's self-expectations for a specific behaviour [53], which originate from a moral obligation to perform a behaviour [55]. Previous scientific studies have shown that personal norms directly affect environmental behaviour [55–57].

In this work, the above-mentioned relations were taken under consideration in order to study the recycling behaviour of Polish consumers. Assuming the importance of the range of information provided on FMCG packaging for effective recycling, selected guidelines covering this issue were also used as the segmentation base.

#### *2.4. Statistical Analysis*

Statistical data analysis was conducted using 3 kinds of tests:


A cluster analysis was conducted in order to segment respondents into groups based on similarities (in the case of the same cluster) and on differences (in the case of belonging to different clusters). Two questions from the questionnaire (15 variables), included in the first and third part of the questionnaire, were taken into consideration. Other questions were used for comparison purposes. All questions were standardised (the Z-score was used) in order to avoid errors. Cronbach's alpha test for the internal consistency of diagnostic tools (questionnaire) was also performed.

### **3. Results**

Cluster Analysis Results

The high value of Cronbach's alpha determined for analysed questions indicated an internal consistency of the questionnaire (0.844). Three clusters were identified due to the consistency of groups and the abundance of members of each group. The final centres of the clusters were shown in Table 2. The mean refers to the standardised value (positive values indicate being above average, negative values indicates being below the average of the question). Table 3 shows a description of the clusters with respect to the demographic attributes.

Cluster 1: *Engaged in green* is characterised by high values of pro-environmental attitudes as well as components related to the respondents' ability to sort waste separately. It comprises of people who express an inner conviction that sorting waste is beneficial for the environment and for society. They are strongly influenced by social values and personal norms.

Cluster 2: *Ecological objectors* is represented by respondents who do not appreciate the benefits of sorting waste to protect the environment and society. They are extremely indifferent to social and personal norms and find sorting waste difficult.

Cluster 3: *Indolent adopters* is described by respondents revealing moderate attitudes towards sorting waste. It is also characterised by an average impact of social and personal norms. Cluster 3 covers respondents who perceived difficulty regarding selective sorting of waste on a medium level.


#### **Table 2.** Results of cluster analysis.

An analysis of the composition of the clusters with respect to socio-demographical attitudes has shown some differences between them (Table 3). Cluster 1 (Engaged in green), the second-largest group in the study (N = 411), constituted 39.94% of the surveyed population. This cluster is dominated by women (60.8%, Chi-square 27.56, *p*-value 0.000), which indicates their strong involvement in environmental issues. Cluster 1 is mainly represented by people between 21 and 40 years of age, with secondary or higher education, who live in cities. Interestingly, this cluster is also characterised by a significant group of people above 51 years of age (Chi-square 19.35, p-value 0.036), which implies that respondents of this age are engaged in the selective collection of waste. Cluster 2 (Ecological objectors) constitutes 11.95% of the studied population. Although this is the smallest group, it is worth observing and analysing in order to recognise the causes for a negative attitude towards waste segregation. This group is dominated by men aged up to 40, with secondary or higher education, living in large cities. Cluster 3 (*Indolent adopters*) is the most numerous group (48.11%, N = 495) among all distinguished. Without a clear gender representation, Cluster 3 is characterised mostly by young people aged 21 to 40, and city dwellers with secondary or higher education. Since it constitutes such a large group of respondents, the lack of conviction may result in the strengthening of attitudes visible in Cluster 2 (Ecological objectors), which, as a consequence, would be decisive for the further efficiency of selective waste sorting. Therefore, intensive information activities and educational campaigns to motivate consumers to adopt pro-ecological habits are of importance. It was also observed that neither the place of residence nor the level of education were significant from the cluster analysis point of view.


**Table 3.** Description of the clusters with respect to the demographic attributes.

The purpose of this study was also to examine the level of actual knowledge of respondents regarding selective waste sorting rules since separate collection is mandatory in Poland, and certain efforts to promote recycling, as well to provide particular guidelines, have already been undertaken at regional and national levels. In order to determine the level of knowledge, respondents were asked to indicate whether the six statements, concerning the separate collection rules of six popular types of household waste, were correct (true) or incorrect (false). Interestingly, the results showed that regardless of the cluster type, the level of actual knowledge of respondents was similar, since the differences between them were statistically insignificant (Tables 4 and 5). As can be seen from Table 4, slightly more than three correct answers (from six questions) were chosen, while the best results were denoted for cluster 1 (Engaged in green) and the worst for cluster 2 (Ecological objectors), however statistically insignificant.


**Table 4.** Description of clusters in terms of the level of knowledge regarding selective waste sorting.

**Table 5.** Results of one-way ANOVA—the level of knowledge regarding selective waste sorting.


<sup>a</sup> No significant differences between clusters with ANOVA (*p*-value > 0.05).

In the case of the rest of the questions, the results were statistically significant, and posthoc tests (the Tukey test) revealed that all clusters differed. Considering the answers in detail, it can be observed from Table 6 that within Cluster 1 (Engaged in green), the worst results were denoted in the case of question 2 (about receipts), since only 28% of the answers were correct. The analysed clusters do not differ significantly in the case of questions 2 (about receipts), 4 (about bottles for edible/engine oil), 5 (about glass containers for drugs), and 6 (about light bulbs). In the case of questions 1 and 3, Cluster 1 (Engaged in green) answered in the best way, while Cluster 2 (Ecological objectors) answered the worst.



Significant differences between the clusters, Chi-square test (<sup>a</sup> *p*-value < 0.05). No significant differences between the clusters, Chi-square test (<sup>b</sup> *p*-value > 0.05)

For further consideration, the questions analysed in the ANOVA analysis were also taken into a cross-table analysis in order to show the distribution of results. Chi-square tests were additionally calculated (Table 7).


**Table 7.** Description of clusters in terms of experience with selective waste collection.

Significant differences between the clusters, Chi-square = 199.1, *p*-value < 0.001.

The results presented in Table 7 show that there are statistically significant differences (Chi-square = 199.1, *p*-value < 0.001) between experiences with sorting waste among the analysed clusters. Respondents concentrated in Cluster 1 (Engaged in green) declared the most frequently that selective waste sorting is easy for them. On the contrary, Cluster 2 (Ecological objectors) is characterised by the highest number of respondents who do not segregate waste. They also declared more often that sorting waste is difficult. Interestingly, it was observed that 1.6% of the total number of respondents declared that they do not segregate waste, although the selective collection of waste is mandatory in Poland.

Moreover, the results revealed statistically significant differences between clusters (Chi-square = 271.9, *p*-value < 0.001) regarding the potential of interactive packaging. Cluster 1 (Engaged in green) covers respondents who declared more frequently that interactive packages can serve as a sustainable communication tool providing information useful for efficient waste sorting (Table 8). Cluster 3 (Indolent adopters) represents a group of respondents with a moderate attitude towards the segregation of waste and the opinion that extended information on packages, regarding sorting waste, can be useful and helpful. In most cases, the obtained values are a little bit below the average, which means that they assessed the potential of additional information as less important. Cluster 2 (Ecological objectors) comprises a group of consumers with negative attitudes towards sorting waste. They also assessed the usefulness of additional information provided on packaging regarding the sorting of waste lower than respondents representing other clusters.

It was also observed that there are statistically significant differences between clusters (Chi-square = 246.3, *p*-value < 0.001) regarding opinions about innovative packaging solutions, such as interactive packages with "extended labels", which are delivering information about the way the product can be prepared for consumption, about allergens, food origins, etc. (Table 9). The results showed that Cluster 3 declared more frequently that interactive packaging could be useful as an attractive and valuable communication tool.


**Table 8.** Description of clusters regarding the potential of interactive packaging as a tool useful for efficient waste sorting.

Significant differences between the clusters, Chi-square = 271.9, *p*-value < 0.001.

**Table 9.** Description of clusters regarding the potential of interactive packaging as a tool for extended information about the product characteristics.


Significant differences between the clusters, Chi-square = 246.3, *p*-value < 0.001.

### **4. Discussion**

A cluster analysis of the obtained results revealed three segments representing different attitudes towards selective waste collection: Engaged in green, Indolent adopters, and Ecological objectors. Engaged in green (48.11% of the total number of respondents) is characterised by consumers highly involved in effective waste sorting. Respondents in this cluster are strongly convinced that sorting waste is beneficial to the environment and society and find it easy. They are influenced by the pressure of social and personal norms. Engaged in green are also the most interested in precise information on how to handle packaging prior to discharging to make recycling more effective. Cluster 2: Ecological

objectors (11.95%) encompasses respondents who do not consider sorting waste as an activity beneficial for the environment or society, nor as a habit. They are poorly influenced by social and personal norms and find selective waste collection difficult. Indolent adopters (39.94%) comprises respondents who perceive the sorting of household waste as moderately beneficial for the environment and society and find it cumbersome. They are rather indifferent to social and personal norms. In light of the above, it can be stated that there is still a need for more intensive information activities and educational campaigns in order to motivate consumers to adopt pro-ecological habits. Moreover, the precise and direct information provided by packaging may promote and facilitate selective waste sorting and enhance the effectiveness of recycling. The discussed results showed some similarities with other studies undertaken by the Market and Opinion Research Agency SW Research in March, June, and October 2020 [15], although different criteria and bases for segmentation were applied. According to the data presented in the above-mentioned report, five profiles of respondents were distinguished: Eco-attentive (35% of the analysed population), Eco-enthusiast (29%), Eco-confused (11%), Sceptical about green marketing (13%), and Eco for show (12%). The most numerous groups are composed of respondents with good environmental awareness (Eco-attentive and Eco-enthusiast), who undertake several pro-ecological activities such as saving electricity or water and sorting waste; however, their actual knowledge of segregation rules was not assessed. Eco-confused do not demonstrate negative attitudes towards pro-ecological activities, but they are passive. Together, respondents described as Sceptical about green marketing and Eco for show constitute a group of people who should be encouraged to get involved and who need the motivation to take part in pro-ecological activities.

The cluster analysis results showed that within Engaged in green, women were the most involved in effective waste sorting. This is coherent with the data provided by the ProKarton Foundation (Poland), which were collected in September 2021, revealing that women segregated waste more often than men [13].

The results of our study also showed that regardless of the cluster type, the level of actual knowledge of respondents about waste sorting rules was similar and insufficient. It implies that notwithstanding the environmental awareness and degree of involvement of respondents in recycling, there is an information gap that hinders the correct sorting of household waste. Our results reflect the current legal situation in Poland, where there is no obligatory labelling of packaging in terms of the type of material or handling hints regarding selective waste sorting. Although there are guidelines for municipalities and residents referring to the selective collection of various types of household waste, laid down by the Ministry of Climate and Environment [58], their application in practice by consumers remains difficult. There are also some discrepancies in separate collection rules among particular regions in Poland, which may contribute to information noise. Our results showed that, similarly, facultative eco-labelling still remains problematic [59]. The most popular examples of eco-labelling used in product packaging are presented below (Figure 1).

It was observed that consumers are often not familiar with their meaning. Moreover, none of them serve as a direct guideline referring to a particular type of waste fraction. Eco-labels are often combined with a set of other symbols concerning the product's characteristics or handling rules, applied within the entire logistic chain (Figure 2). However, it must be underlined that excessive labelling or improper application is not communicative but, rather, confusing. Misleading consumers and greenwashing are legally prohibited.

**Figure 1.** Chosen types of eco-labelling: (**a**) dispose of according to the local regulations, (**b**) reusable packaging, (**c**) packaging suitable for recycling, (**d**) packaging material type: 1—poly(ethylene terephthalate). Source: (**a**) CSN 77 0053 Packaging—Packaging waste—Instructions and information ˇ on manipulation with used packaging, Obaly—Odpady z obal ˚u—Pokyny a informace pro nakládání s použitým obalem [60]; (**b**–**d**) Ordinance of Minister of Environment on the templates of packaging labelling of 3 September 2014 [61].

**Figure 2.** An example of a purchase packaging that conveys information concerning the product's characteristics and handling rules.

It is worth noting that these issues are considered highly important at the community level, while the packaging industry and consumer product manufacturers endorse the need for relevant and consistent information on how to segregate household waste correctly in order to support circular economy initiatives [62]. Simultaneously, in the Polish market, there are initiatives undertaken by several retailers regarding the labelling of packaging with a particular fraction of waste [63]. However, the proposed systems are not coherent due to the different symbols used to indicate selective waste sorting rules or to provide detailed information about particular packaging elements when the packaging is composed of varied materials.

In light of the above, the information should be precise, detailed and reliable. In some cases, two-dimensional labelling may be enhanced with interactive packaging solutions in order to provide additional assistance. Digital packaging offering virtual content, provided by QR codes, augmented reality, or invisible watermark coding, enables customised features, content, and style and opens a new way of communication with consumers. It may also provide professional information which is not available on a traditional label. Therefore, the interest in such a tool was taken into consideration. The results showed that 87.4% of respondents representing *Engaged in green* and 68.7% from *Indolent adopters* declared that extended information provided by interactive packaging would be useful (33.6% and 50.9%, respectively) and very useful (53.8% and 17.8%, respectively) in household waste sorting. The survey results are a part of the project "Interactive packaging as a new communication tool on B2C market" conducted from 1 September 2020 to 28 February 2022, devoted to the exploration of consumers' experience with interactive solutions using qualitative and quantitative research methods.

### **5. Conclusions**

The results showed that consumers' recycling behaviour is influenced by personal norms and behavioural intentions as well as their actual knowledge. A segmentation analysis revealed important discrepancies between respondents, who were profiled into three clusters: *Engaged in green*, characterised by high values of pro-environmental attitudes; *Indolent adopters*, described by respondents revealing moderate attitudes towards sorting waste; and *Ecological objectors*, who do not appreciate benefits of sorting waste. Therefore, tailored communication and marketing activities regarding different types of consumers should be proposed to promote pro-environmental attitudes. Regardless of the cluster type, the level of the actual knowledge of the respondents about waste sorting rules was similar and insufficient. It implies that notwithstanding the environmental awareness and degree of involvement of respondents in recycling, there is an information gap that hinders the correct sorting of household waste. Assessing the role of packaging as a tool affecting separate waste collection, special attention should be paid to the information it provides since a majority of respondents (*Engaged in green* and *Indolent adopters*) declared that more precise guidelines are needed in order to facilitate the sorting of waste, which in fact determines the effectiveness of recycling. Our study highlighted the need for a mandatory, precise, and coherent system of packaging labelling in order to provide consumers with explicit and comprehensible recycling guidelines. Confused consumers, even those involved in pro-ecological activities, turn their doubts into recycling mistakes.

### **6. Research Limitations**

The limitations of this study include the fact that the survey was conducted using the CAWI method, including internet users only, which do not fully cover the country's population. However, the survey encompassed a representative sample in terms of gender, age, and education according to data from the Polish Central Statistical Office and the SW Research Market and Opinion Research Agency's panel of respondents. Secondly, the cluster analysis reflects the attitudes of respondents among the Polish population, considering actual legal requirements in Poland. Therefore, although selective waste management is one of the key elements of the EU environmental policy, national perspectives may differ within the other Member States, while recommendations regarding post-consumer waste collection and segregation systems are not homogeneous. Nevertheless, the authors assume that the obtained results may be useful not only from a national perspective but also contribute to a wider discussion regarding the informative value of packaging on the European market and its potential in supporting the environmental attitudes and activities of consumers.

**Author Contributions:** Conceptualisation, methodology, investigation, writing—original draft preparation, review and editing: P.W. and K.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** The project financed within the Regional Initiative for Excellence programme of the Minister of Science and Higher Education of Poland, years 2019–2022, grant no. 004/RID/2018/19, financing 3,000,000 PLN.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Acknowledgments:** The authors gratefully acknowledge the financial support of the Minister of Science and Higher Education of Poland ("The project financed within the Regional Initiative for Excellence programme of the Minister of Science and Higher Education of Poland, years 2019–2022, grant no. 004/RID/2018/19, financing 3,000,000 PLN").

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**

