ICCS 2009 Technical Report - IEA

During the multiple regression analysis of expected electoral and active political participationreported in Chapter 8 of the extended (international) ICCS report (Schulz et al., 2010b, pp.235ff ), an approach similar to that used for the multilevel analysis of civic knowledge wasused to account for missing data. However, although civic knowledge scores were at hand forall assessed students during the multivariate analysis of the two questionnaire scales (expectedelectoral and active political participation), scores for many students for these two dependentvariables were not available.On average, across countries, nine percent of students did not have complete data forall variables in the model; in two countries (the Dominican Republic and Paraguay), thepercentages were considerably higher—above 20 percent. For 8 of the 11 predictor variables,missing values were substituted with means (for continuous variables) and medians (forcategorical variables), and eight dummy indicators were added to the set of predictor variables.The results for these additional variables are not included in the tables.Missing indicators for a number of student variables were computed during the multipleregression analysis. These variables were as follows:• Sense of citizenship self-efficacy;• Students’ internal political efficacy;• Students’ interest in political and social issues;• Students’ trust in civic institutions;• Students’ reported parental interest in political and social issues;• Students’ past or current participation in civic activities in the community;• Students’ past or current participation in civic activities at school; and• Students’ support for political parties.Missing treatment was not done for those variables in the model that showed lower proportionsof missing data.Table 13.6 shows the unstandardized regression coefficients for the missing indicators forthe multiple regression analysis of expected electoral participation; Table 13.7 shows thosefor the analysis of expected political participation. Missing indicators tended to be negativelyassociated with expected electoral participation. Most of the coefficients were not, however,significant.Table 13.8 records the numbers of students included in both regression models in comparisonwith those that were assessed in ICCS. For both regression models, about 93 percent of cases,on average, remained in the analysis (the range across countries was 70% to 99%). In twocountries (the Dominican Republic and Paraguay), more than 15 percent of the respectivesamples were excluded. The results for these countries are annotated in the reporting tables.274ICCS 2009 technical report