**1. Introduction**

Happiness and life satisfaction are currently central themes of research in social sciences, psychology, philosophy and economics [1]. Much of the work has been based on determining more objective methods of research on happiness, well-being and quality of life, supported by socioeconomic and geographical attributes, with a special interest in the impact of inequalities, such as social justice, social and spatial [2]. Equally, however, numerous studies have emerged that consider more subjective characteristics through the use of social surveys [3], where citizens rate their health, well-being, life satisfaction, as well as their happiness in general [4].

The measurement and analysis of happiness is becoming increasingly important in the social sciences [5], where there have been numerous attempts to define, measure and analyse subjective measures of happiness from the perspective of different academic disciplines, from neuroscience and psychology to philosophy and economics [6]. Thus, happiness has been shown to be one of the key factors in subjective well-being and overall life satisfaction [7–12], and it is very related if you take into account the place where a person lives, especially in the cultural context [13]. Thus, the current vision of urban, economic and social policy in cities is taking on particular importance [14], with the aim of

**Citation:** Huete-Alcocer, N.; López-Ruiz, V.-R.; Alfaro-Navarro, J.L.; Nevado-Peña, D. European Citizens' Happiness: Key Factors and the Mediating Effect of Quality of Life, a PLS Approach. *Mathematics* **2022**, *10*, 367. https://doi.org/ 10.3390/math10030367

Academic Editors: Pedro Antonio Martín Cervantes, María del Carmen Valls Martínez and José-María Montero

Received: 23 December 2021 Accepted: 22 January 2022 Published: 25 January 2022

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understanding the happiness of their residents [15,16]. The place where one lives affects all aspects of everyday life and, therefore, affects one's happiness [15,17,18]. In this regard, authors such as [19] have examined whether the happiness of citizens depends on the amount of services available in a city. Their results reveal that they must have a good quality of services, for example: surveillance, schools, beauty, easy access to health, as well as transportation services and cultural and recreational opportunities. In this sense, this is what really determines whether cities will succeed or fail when residents are presented with opportunities to have a good quality of life. In view of the above, this study uses a subjective approach for measuring happiness in order to analyse how it is influenced by both personal elements and external factors simultaneously [20].

The purpose of this research is to gain a better understanding of how some key factors influence the happiness of European citizens since people normally tend to choose where to live based on job opportunities, as well as the services and public goods offered [15]. To that end, a factor analysis using the Flash Eurobarometer 419 from 2015 [21] produced by Eurostat has allowed us to identify some key aspects of cities for citizens, according to their degree of satisfaction with them. The factors identified measure citizens' satisfaction with safety, environmental actions and urban planning. Thus, we first conduct a literature review to observe how the literature approaches these factors before analysing the effects they have on happiness, considering both the direct effect of each factor and the indirect effect, mediated by quality of life. Specifically, the Flash Eurobarometer 419 compiles European citizens' assessments of different items relating to various aspects of their personal situation, their city and the neighbourhood where they live. It should be noted that this information has been filtered, taking into account some of the specifics of this study, allowing us to identify the three key factors mentioned above.

Thus, in Section 2, we conduct a literature review that allows us to confirm the use of quality of life as a mediating variable, as well as the theoretical justification for each of the hypotheses established in the article. Section 3 details the methodology applied in this research, the database used, the definition of each of the factors considered and the procedure used to fit the corresponding model. The results and discussion are presented in Section 4 where the measurement of the model and the validation of the hypotheses proposed in this study are shown. The method chosen has been through structural equations (SEM), using the technique of partial least squares (PLS). This technique has become a standard tool for analysing complex interrelationships between variables [22,23] and is used in many disciplines [24]. Section 5 outlines the main conclusions reached, together with the new lines of research opened up.

#### **2. Background on Happiness and the Mediating Effect of Quality of Life**

Regarding the measurement of happiness, Veenhoven [25] and Diener and Seligman [26] hold that happiness reveals an individual's assessment of the general aspects of their life and conditions, and how much an individual likes the life that he/she lives. Therefore, the central concept of happiness is the subjective assessment of one's life or satisfaction with life [7,27]; they thus claim that happiness can be measured through "Satisfaction with life in this city". This way of measuring happiness is supported by the works of Diener [28], Diener and Inglehart [29], Veenhoven [30] and Bernini, Emili and Galli [31]. In addition, Moeinaddini et al. [32] consider that happiness is synonymous with satisfaction of the experience, and this satisfaction can come from everything around you. Therefore, the place where one lives affects happiness [33]. In this study, we follow this subjective approach, establishing that the way to measure residents' happiness with their city is through the answer to the question "I am satisfied to live in . . . ".

The literature review has allowed us to observe how the terms happiness and quality of life are intertwined, given the links between them. While there are studies that clearly differentiate between quality of life and happiness by measuring quality of life through aspects, such as income [34], income and employment [35] or the built environment, education, leisure and recreation, mental and physical health, social belonging and safety

and crime. [16,36]. Other studies support that quality of life is synonymous with more abstract issues, such as freedom, human rights and happiness. [37], which complicates the task of differentiating between quality of life and happiness. In this respect, we consider quality of life as a mediating variable that can contribute to happiness. Accordingly, we approach quality of life as a multidimensional concept, accounting for different aspects that allow us to measure citizens' quality of life. It is worth highlighting the work of [14,38], which have served as a starting point for our study.

W˛eziak-Białowolska [14], using the Flash Eurobarometer 366 [39] proposes measuring quality of life in relation to citizen's satisfaction with aspects, such as availability of services, the environment and social aspects in cities and characteristics of the city, such as size, location, safety, economic development, the labour market and the quality of institutions. Thus, the results indicate that satisfaction with life in a city is very different, both within cities and across Europe. In the same vein, Nevado-Peña et al. [38], based on the Flash Eurobarometer 419, proposes four dimensions for the measurement of the quality of life of European citizens: Life Satisfaction (Trust and Safety), Mobility (Culture and Sports), Integration (Sustainability) and Public Services.

This way of measuring quality of life allows the researcher, on the one hand, to analyse its direct influence on happiness and, on the other, to consider it as a mediating variable of the effects on happiness. This allows more in-depth research on what aspects to promote in order to ultimately achieve greater happiness in European citizens. In this regard, it is necessary to establish different hypotheses to be tested in this study.

#### *2.1. European Citizens' Happiness: Hypotheses Development*

From the literature review, we draw our first hypothesis on the relationship between quality of life and happiness. Senasu and Singhapakdi [40] analyse the influence of quality of life on the happiness of Thai citizens in family, community and work settings. Li [41] uses objective, subjective and social quality indicators for three Chinese cities, analysing the relationship between respondents' happiness and quality of life characteristics (objective and subjective) and social quality. Finally, several analyses have found that, among the three abovementioned sets of factors, the ones that most influence happiness are subjective indicators [31,42]. Thus, we propose the following hypothesis to determine whether happiness in European cities can be influenced by people's subjective assessment of their quality of life:
