The impact of sibling size on children's academic performance; a case study of female high school students in Tehran

The present study addressed the relationship between sibling size and children's academic performance. One common scientific and cultural belief is that children's academic performance declines with the increase in sibling size. However, this belief has not been subjected to empirical research in Iran. The data were collected by electronic questionnaire from 493 secondary high school female students in Tehran. The results revealed sibling size had a weak and negative relationship with the students' academic performance. However, this relationship lost its significance after controlling for some intervening variables. As a result, it can be argued that increasing the sibling size alone does not affect the academic performance. The multiple regression indicated that the intervening variables of self-efficacy, self-esteem, time spent with parents, and school type - public or non-profit - affect academic performance. This means that instead of the number of children, policymakers should focus on modifying these effective intervening variables.