3.4. Citizens’ Perceptions Analysis of RES Usage and Their Contribution to Life Quality
The Principal Component Analysis (PCA) method is used to facilitate the logit models on questions concerning respondents’ opinion on RES. In this method, each identified component interprets a rate of variance that has not been interpreted by previous components. A proportion of 60% of the variance is needed to be interpreted by the factors that arise in social sciences [
46]. The criterion for the selection of factors is for the eigenvalue to be greater than 1, known as the Kaiser criterion. The Kaiser–Meyer–Olkin sample measure equals to 0.86; thus, it is proven that factor analysis is acceptable. This is also validated by Bartlett’s test of Sphericity, where sig. = 0. The final number of factors was determined by applying the Principal Components method based on varimax rotation. Nine factors that have eigenvalues greater than 1 have emerged, explaining a total of 68% of the observed variance. An internal affinity test was performed by using Cronbach’s alpha coefficient for the 40 questions used in the factorial analysis, returning a value of 0.884 which is considered to be high [
46].
Regarding the nature of the questions that have been assigned to the factors, the following profile of factor interpretation was concluded, as presented in
Table 3.
As it can be seen in
Table 3, a new set of 9 variables—out of the initial 40 Likert scale questions of the questionnaire—was formulated. The interpretation of each component separately is carried out by commenting on the social assessment variables that they represent.
The first component (F1) is identified as “RES perceived benefits”. It explains 13.7% of the total variance of the variables that are included in the analysis and it is considered as the most important factor. The questions/variables that are associated with the highest loadings in this factor are: “RES promote green growth” (84.4) and “RES promote environmental protection” (83.7).
The second component (F2) explains 11.4% of the total fluctuation and is identified as “RES perceived disadvantages”. This component is mainly determined by the questions/variables: “RES have a low rate of return” (86.1) and “are not profitable throughout the year” (83.4).
The third component (F3) refers to investment incentives for RES and explains 8.7% of the total variance. It is mainly formed by questions/variables such as “subsidized system maintenance” (78.8), “deduction of installation costs from taxable income” (77.1) and others.
The fourth component (F4) explains 7.6% of the total variance and is mainly composed of the following questions: “Public information from the local authorities” (75.8), “Public information from the state” (71.2), “well defined legal framework” (63.7). This component is identified as “RES actions for expansion”.
The fifth component (F5) explains 7.4% of total variance and is identified as “Social Barriers to RES Promotion” since the variables representing the highest load on this factor are “Lack of Knowledge” (83.0) and “Lack of Information” (79.9).
The sixth component (F6) explains 5.8% of the total variance and is identified as “Economic barriers to the promotion of RES” since the variable representing the highest load on this component is “High installation costs” (84.6).
The seventh component (F7) explains 5.1% of the total variance and is identified as “Fossil fuel price relative to RES” as the variable representing the highest load on this factor is “If the cost of oil is appreciably expensive” (90.7).
The eighth component (F8) explains 4.9% of the total variance and is identified as “Effect of a social-legal framework on RES use” since the variables that represent the highest load on this component are “I would use RES if it were also used by fellow citizens” (83.0) and “Lack of complete legal framework” (70.7).
Last, the ninth component (F9) explains 3.1% of the total fluctuation and is identified as “Purchase of RES system with interest-free installments” with the factor load being 71.8.
In the first stage of our analysis, we focused on exploring the variables that are associated with whether a respondent is a RES user or not. For this purpose, we applied a binary logit model where the variable “use of RES (yes/no)” was determined as the dependent. The previously identified factors were used as explanatory variables based on a relevant study [
47]. The selection of the most appropriate model was based on the applicability of the backward method. Hosmer-Lemeshow’s test (sig. = 0.001) further indicated that the dependent variable values did not sustain a statistically significant difference from the values provided by the model, thus, the model is considered applicable [
48]. Nagelkerke’s pseudo-R Square statistic showed that the final iteration (step 6) explained a percentage of 15% of the dependent variable [
49]. Out of the 9 initial independent variables (F1 to F9), the stepwise binary logistic model retained 4 variables at the 90% confidence level. Those statistically significant variables are F1 (RES perceived benefits), F5 (Institutional promotion barriers for RES), F6 (Economic barriers for RES), and F7 (RES price compared with conventional fuels). The final model for the estimation of RES users is presented in
Table 4.
The final model based on the above table data is the following one:
By estimating Exp(B), the odds ratio was calculated. For example, the odds ratio coefficient, under column Exp(B) of F1 means that by keeping all the other explanatory variables at a fixed value, we will see 0.54% increase in the odds of a respondent belonging to the category of “RES user”, for a one unit increase in F1 (RES perceived benefits), since Exp(0.618) = 0.539. The same explanation applies to variable F7. On the other hand, the negative coefficient of variables F5 (RES social promotion barriers) and F6 (RES economical promotion barriers) mean that they are negatively associated with RES use. This means that non-RES users consider those barriers (high cost and social barriers as information lack, lack of confidence, the role of the state) to be determining and, at the same time, they seem to overlook the RES advantages.
To validate the proposed model of estimation of RES users, we tested the relationship between each of the independent variables with the dependent variable “RES use (yes/no)”, by applying the Mann–Whitney U method, as presented in
Table 5. By looking at the statistical significance index (sig. < 0.05) in
Table 5, all four independent variables were found to be related to the dependent variable.
The binary logistic model correctly identified 70.2% of all cases. The success rate for “RES users” is 87.7%, as it correctly identifies 206/235 of the respondents, whereas the success rate range for the “non-RES users” category is narrowed down to just 45.1%, as it correctly identifies 74/164 of the respondents.
In the second stage of our analysis, we focused on examining the factors that shape respondents’ opinion about RES’ contribution to life quality improvement. All nine factors generated by the above factor analysis procedure were used. Carrying an ordinal regression with the stepwise method in STATA, it was noticed that the final model retained only four factors as independent variables, as the others were removed due to the pr (0.10) criterion. The reference category was that of “strongly agree” as shown in
Table 6.
The final model here, based on the above table data is the following one:
In the above model,
j = 1, 2, 3 are the categories of the dependent variable (4 − 1 = 3). The p-value (sig. = 0) indicated that the model was statistically significant compared to the null model without any explanatory variables. The pseudo-R
2 coefficient equaled to 0.4665 suggesting a strong model in accordance with a relevant statistical table [
49]. By estimating Exp(B), the odds ratio was calculated and noted to be higher than 1 for the four independent variables (F1, F2, F3, and F4), suggesting, in most of the cases, a positive correlation between the independent variables and the dependent variable. More specifically, for a one-unit increase in variable F1 while keeping the other variables constant, the likelihood of the category “strongly agree” increases at 1 − Exp(2.799) = 1542%. Respectively, for an increase of one unit in variables F3 and F4, the probability of the category “fully agree” is increased by 65%, and 110%, respectively. Lastly, for an increase of one unit in variable F2, the probability of the category “fully agree” is decreased by 34%.
To validate the proposed ordinal model, we verified the condition of proportionality with the combined utilization of the Brant test in conjunction with the parallel lines in STATA. Finally, three stepwise binary logistic regression models are presented in
Table 7, by using life quality as the dependent variable (whether respondents agree that the use of renewable energy improves life quality) and setting as independent variables the four factors (F1, F2, F3, and F4) that were statistically significant in the ordinal logistic regression. A filter was used for the data selection to compare two categories at a time, for the four-category variable life quality (disagree, neutral, agree, and strongly agree). Thus, by taking the “strongly agree” statement as a reference category, three logit models were formulated, all meeting the acceptance criterion of Hosmer and Lemeshow [
48].
Moreover, by checking the goodness of fit for the three models with the Nagelkerke pseudo-R Square index, the model between “strongly agree” and “neutral” sustained the highest level of adaptation to the data with R
2 = 0.805 as presented in
Table 8.
Concerning the predictability of the three binary logistic models, they can determine in which category a respondent belongs concerning his views about RES contribution to life quality, as captured by F1 to F4. Regarding the Exp(B) column of
Table 8, we concluded that in all three models, variable F1 “RES perceived benefits” is the main determinant of “strongly agree”. Model 1 includes F1–F4 as significant between the categories of “agree” and “strongly agree”. Model 2 retained F1 and F4, the “RES actions for expansion”, as statistically significant. This model distinguishes between the neutral position towards RES and the strong positive position. Model 3 determines between the categories of “strongly agree” and “disagree” while the stepwise method retained only variable F1 as statistically significant.
By looking at
Table 9, we notice that out of the three proposed models, the second one has the highest predictability of 94.4%.
By examining the logit models, we noticed that if a person has a completely negative attitude towards RES contribution to life quality and is found on the “disagree” category of the 5-point Likert Scale, it is possible to move to the “agree” category by a minor increase in the perceived benefits from RES. Furthermore, if a person is already found in the “agree” category, an increase in all the four variables is needed to move to the “strongly agree” point of the scale. Finally, if a person has a neutral position towards RES contribution to life quality, an increase is needed to the variables concerning RES perceived benefits and RES actions for expansion to move to the “strongly agree” category.