To address the equivalence of scores across countries, youth in the U.S. and Canada were compared on the Conners 4. Cross-cultural differences were expected to be minimal, and the lack of meaningful differences would support the generalizability and utility of the Conners 4 in both countries.

The invariance of the factor structure was compared based on the youth’s country of residence. Results examining MI between the U.S. (N = 2,838 for Parent and N = 2,563 for Teacher) and Canada (N = 376 for Parent and N = 301 for Teacher) are found in Tables 10.23 and 10.24. MI for Self-Report was not explored due to the small sample size for Canadians (N = 199), as the large number of items on the scales (N = 60 Content Scale items on Self-Report) and ordinal nature of the items requires a more substantial sample size.

For Parent, the results (as seen in Table 10.23) indicate no meaningful change across models. The Satorra-Bentler χ² test was significant for the intercept model, but other fit statistics did not decline, indicating no meaningful change and therefore no compromise regarding invariance. Across the Conners 4 Teacher scales (as seen in Table 10.24), there were no statistically significant reductions in the Satorra-Bentler χ² test or any declines in the majority of model fit statistics when comparing different levels of invariance. Because the Conners 4 meets the most stringent level of invariance tested in terms of country of residence, these results support generalizability of the Conners 4 Parent and Teacher forms to both American and Canadian youth regarding factor structure, loadings, thresholds, and intercepts.

Next, differential test functioning was evaluated with regard to country of residence. DTF results are presented graphically in Figure 10.3 for the Inattention/Executive Dysfunction scale, as an example of the trends seen across all scales and rater forms. Test functioning curves for youth in the U.S. and Canada are depicted, along with a shaded band to display a 95% confidence interval; the two groups’ curves are almost completely overlapping, demonstrating a lack of difference between groups. Results in terms of effect sizes of the DTF analyses for all forms are presented in Table 10.25. Negligible differences between countries were found (i.e., effect sizes at or below |.06|), which further supports the generalizability of the Conners 4 to U.S. and Canadian populations alike.

Figure 10.3. Differential Test Functioning by Country of Residence: Inattention/Executive Dysfunction

a) Parent	b) Teacher
c) Self-Report

To examine observed group differences between countries, a subsample of the youth from the U.S. were randomly selected to match the sample of Canadians from the Normative Samples. Youth were matched by gender, PEL (PEL was matched for Parent and Self-Report only), language(s) spoken, clinical status, and age. Refer to Table F.43 in appendix F for the demographic characteristics of the American and Canadian paired samples for all Conners 4 forms. Details about the raters for the Parent and Teacher samples are provided in appendix F in Table F.44.

The paired samples of Americans and Canadians were then compared for significant differences across mean scores. Results of the ANOVAs and descriptive statistics for each scale are presented in Tables 10.26 to 10.28. Across all rater forms and all scales, there were no statistically significant effects of country of residence. Ratings of youth from the U.S. and Canada resulted in very similar mean scores as described by Cohen’s d; all reported effect sizes were negligible to small (with Cohen’s d ranging from 0.00 to |0.31|). These results indicate that country of residence (specifically, U.S. vs. Canada) had no significant effect on the Conners 4 scale scores. Along with the results of MI and DTF demonstrating equivalence, there is evidence that the Conners 4 is appropriate for use with American and Canadian populations alike.