9. You are interested in environmental factors that may be associated with children's physical health. You run three regression models, adjusting for additional variables in each model. The results of your cross sectional study are below.

kidsgoodhealth= child's health score (ordinal variable, 1-5, higher number = healthier)

insurance = family has health insurance (binary variable, 0=no, 1=yes)

familySES = family income level (ordinal variable, 1-8, higher number = higher income)

college = did someone in the household go to college? (binary variable, 0=no, 1=yes)