Which of these are threats to validity in the study

Last updated: 2/8/2023

Which of these are threats to validity in the study Professor Jones wants to study aggression in preschool children He predicts that children from poorer incomes will be more aggressive than children from richer backgrounds So he contacts all his friends who have preschool children and from this group he assembles a sample of 20 children ranging in age from 2 years to 5 years After asking their parents how much their yearly income level is Professor Jones observes each child at play in their local playground He counts the number of times that child hits another child Since he gets observe an equal number of rich and poor children hitting others he concludes that poor children are as aggressive as rich children small sample owing biased sample