Overweight and fast-food restaurants, continued. In the article, the researchers state:

(1) "CIs were adjusted for clustering at the school level"; and

(2) "All models also included controls for the following student characteristics: a female indicator, grade indicator, age indicator, race/ethnicity indicators, and physical exercise indicators.

All models also included indicator variables for school location type, including large urban, midsize urban, small urban, large suburban, midsize suburban, small suburban, town, and rural."

(a) What violation of the response distribution is Statement 1 addressing? Explain your answer.

(b) Explain why the researchers controlled for the variables described in Statement 2 when looking at the relationship between overweight and proximity.