Green returns to education: Does education affect pro-environmental attitudes and behaviors in China?

behaviors. Otherwise, it may just reflect some province-specific structural changes other than the implementation of the CSL that are correlated with pro-environmental attitudes and behaviors. To check the validity of this assumption, we conduct a placebo test. Specifically, we assume that the CSL had been implemented five years earlier than the actual implementation year of each province and re-run the regressions as Eqs (2) and (3) using the false reform expo- sure as the instrument. We expect that the false reform exposure has no impact on individual education levels and, more importantly, no impact on pro-environmental attitudes and behaviors. Columns (1) and (2) of Table 6 show the results of the placebo test. Obviously, the coeffi- cients on the false reform exposure are insignificant in both stages of regressions. This finding substantiates the validity of our instrumental variable and indicates that the benchmark results are reliable. 4.3.2. Alternative pro-environmental attitudes and behaviors. We further verify whether our benchmark results are robust to alternative measure of pro-environmental atti- tudes and behaviors constructed by factor analysis. Factor analysis takes into account the cor- relations between answers to different attitudes/behaviors questions and the random error in measurement [46]. Specifically, we obtain an index of pro-environmental attitudes by per- forming a factor analysis on the three attitudes questions and an index of pro-environmental behaviors by performing a factor analysis on the six behaviors questions. The two indexes

serve as alternative measures of pro-environmental attitudes and behaviors. We run 2SLS regressions with the alternative measure of pro-environmental attitudes and behaviors as the dependent variable and present the results in columns (3) and (4) of Table 6. Obviously, in both regressions, the estimates of education are positive and highly significant, suggesting that the positive impacts of education on pro-environmental attitudes and behav- iors are robust to alternative measure of pro-environmental attitudes and behaviors. Table 6. Robustness checks. Placebo test Alternative pro-environmental attitudes and behaviors Sample with shorter birth cohort span Pro-environmental attitudes Pro-environmental behaviors Pro-environmental attitudes Pro-environmental behaviors Pro-environmental attitudes Pro- environmental behaviors (1) (2) (3) (4) (5) (6) Education 0.146 0.145 0.043�� 0.042�� 0.022�� 0.009�� (1.104) (0.108) (0.017) (0.018) (0.008) (0.004) Controls Yes Yes Yes Yes Yes Yes Observations 3,337 3,542 3,456 3,661 2,403 2,511 First-stage estimation CSL 1.052 1.052 2.937��� 3.141��� 1.794��� 1.841��� (0.693) (0.693) (0.258) (0.262) (0.283) (0.273) F-statistics 2.31 2.31 129.41 143.44 40.07 45.31 Note: The table reports the estimates from three robustness checks. 2SLS models are used for estimation. In columns (1)-(2), two placebo tests are conducted based on the assumption that the CSL had been implemented five years earlier than the actual implementation year of each province. In columns (3)-(4), alternative pro-

environmental attitudes and pro-environmental behaviors obtained from factor analysis are used as the dependent variables. In columns (5)-(6), the sample is restricted to individuals born less than 16 year earlier than the first CSL-affected cohort. All regressions have the same controls as in column (2) of Table 3, but their coefficients are suppressed for brevity. Robust standard errors are clustered at the cohort-city level and are reported in parentheses. ���, �� and � indicate 1%, 5% and 10% significance levels, respectively. https://doi.org/10.1371/journal.pone.0263383.t006 PLOS ONE Green returns to education PLOS ONE | https://doi.org/10.1371/journal.pone.0263383 February 3, 2022 14 / 20