*2.5. Research Model*

The research model of our research case is based on TAM, as described in the previous section, and is presented in Figure 3 below. The external factors grouped in personal (PCIL), organizational (OPC), and technological (STC) groups of factors are expected to affect the construct PU and construct PEOU of ERP systems, along with the construct WC. In Figure 3, Davis's initial TAM research model [75,76] is marked in grey. As already mentioned, construct PEOU has an impact on the construct PU, while both influence construct AT and that further has an impact on the construct ExU by employees.

Regarding the use of ERP systems by its users, we can assume, as already mentioned, that a relation among construct WC and construct PU exists, as well as the direct impact of the construct WC on construct AT and on the construct ExU.

**Figure 3.** Conceptual Model [30–32,65]; extended by the authors.

Hypotheses that reflect the dependencies and directions of relationships are based on the TAM model and its extensions [22,27,32–35,64,72,82–84]. Therefore, we hypothesized:

**H1.** *PEOU of ERP use has direct positive impact on PU of ERP use.*

**H2.** *PEOU of ERP use has direct positive impact on AT towards ERP use.*

**H3.** *PU of ERP use has direct positive impact on AT towards ERP use.*

**H4.** *WC with ERP users' job description tasks has a direct positive effect on their PU of ERP use.*

**H5.** *WC with ERP users' job description tasks has a direct positive effect on AT towards ERP use.*

**H6.** *WC with ERP users' job description tasks has a direct positive effect on the ExU.*

**H7.** *AT towards ERP use has a direct positive effect on the ExU.*

The issue of the TAM research model-based studies that are focused on ERP systems is that many of them include a very modest range of external factors influencing user acceptance and use of these systems [33,34]. When ERP systems are used in companies, a larger number of external factors may be important for shaping ERP user acceptance. Consequently, for higher-order factors, it may be important to group several external factors together. In our research, the factors of the second order were formed when hypothesizing the following:

**H8.** *A conceptual external factor of personal characteristics and information literacy (PCIL) statistically significantly influences the antecedents of AT and ExU.*

**H8a.** *A conceptual external factor PCIL statistically significantly influences the WC.*

**H8b.** *A conceptual external factor PCIL statistically significantly influences the PU.*

**H8c.** *A conceptual external factor PCIL statistically significantly influences the PEOU.*

**H9.** *A conceptual factor of the system and technological characteristics (STC) statistically significantly influences the antecedents of AT and ExU.*

**H9a.** *A conceptual external factor STC statistically significantly influences the WC.*

**H9b.** *A conceptual external factor STC statisticalˇcy significantly influences the PU.*

**H9c.** *A conceptual external factor STC statistically significantly influences the PEOU.*

**H10.** *A conceptual factor of organizational-process characteristics (OPC) statistically significantly influences the antecedents of AT and ExU.*

**H10a.** *A conceptual external factor OPC statistically significantly influences the WC.*

**H10b.** *A conceptual external factor OPC statistically significantly influences the PU.*

**H10c.** *A conceptual external factor OPC statistically significantly influences the PEOU.*

#### *2.6. Research Approach*

For our research study, we chose an international corporation that consisted of several subsidiaries which operated in the automotive industry in four countries. Researching ERP systems and their acceptance in the automotive industry is the topic of several researchers. Published research, in the majority of cases, applies TAM as a research model for different aspects of technologies and information systems, including researching ERP acceptance [99–104]. Therefore, we used TAM as basic research model to study the international corporation, which consisted of companies which are suppliers producing car components/parts for major car producers worldwide. Because the study aimed to research ERP use in its mature stage when ERP is used at an advanced level and because we wanted to research its use in different organizational cultures, we selected these companies. They implemented SAP ERP systems 19 years ago and conducted several upgrades to the systems used. The companies involved are in four countries and employ more than 4000 employees. We addressed a random sample of users in these companies, consisting of 860 employees who have been using the ERP system for several years and can be considered advanced users. We sent them e-mails with invitations and a link to the web questionnaire.

The questionnaire was prepared in four languages (Slovenian, Serbian, Croatian, and the Bosnian and Herzegovinian language) according to the international character of the of companies studied. Before starting a survey, a pilot study took place, which included a group of ERP advanced users and a group of key users from different companies. Based on their feedback, a few minor changes were made to make the questions more understandable to respondents in different countries. The elements with the missing data were excluded, resulting in 208 valid questionnaires that were further analyzed (24.19%).

The empirical data were analyzed in the five stages of the methodological approach involving the PLS-SEM by using SmartPLS 3 [46] and the ANN analysis by using IBM SPSS 20, as follows:


While analyzing data, the approaches defined by Henseler et al. [37] and Garson [38] and Hair et al. [43,45] were implemented.

#### **3. Results**

#### *3.1. Description of the Sample*

Table 1 displays the sample structure details. Among respondents, 27.4% (57) were female and 72.6% (151) were male, and all were employees and users of the implemented ERP system. The majority, over 65%, reported to have at least some higher education; others reported secondary educational levels or less. Sample characteristics are in Table 2.


**Table 1.** Number of responses per country.

\* in a multinational group of manufacturing companies in the automotive industry

**Table 2.** Descriptive statistics of respondents' characteristics.


Collected data show that respondents use the ERP system for about three hours daily. 59.1% (123) are employed in positions at the operational level (e.g., professional experts and other similar positions), 29.3% (61) are managers at the low level (e.g., manager of a group or manager of anorganizational unit), 20.6% (22) are managers at the middle level, and 1% (2) are managers at the corporate governance and/or top management level. The total working experience equals, on average, 16.1 years, while the average working time at the current position equals 8.1 years.
