Bias in Recruited Sample Research on Children with Same-Sex Parents Using the Strength and Difficulties Questionnaire (SDQ)

Aims: To test for the presence of bias on use of a common psychometric instrument, the Strengths and Difficulties Questionnaire (SDQ), in studies of children with same-sex parents using a recruited convenience sample.
Study Design: Non-parametric quasi-experimental two-group comparison.
Methodology: Results from five qualifying studies, two with random samples and three with recruited samples, were compared with normative population data, assessing the percent of comparisons favorable or unfavorable to children with same-sex parents for six subscale measures.
Results: In the recruited samples 79.3 % (range: 75-83) of comparisons were favorable to children with same-sex parents, compared with no favorable comparisons (0%, range 0-0) in the random samples. Two additional random samples with related measures were also adduced, also with no favorable comparisons (0%, range 0-0).
Conclusion: Evidence suggests strong bias resulting in false positive outcomes for parent-reported SDQ in recruited samples of same-sex parents.