A researcher is interested in the impact of joining a weight loss program in the past 12 months on the individuals weight loss. The analysis was restricted to people aged 16 and older who answered yes...

A researcher is interested in the impact of joining a weight loss program in the past 12 months on the individuals weight loss. The analysis was restricted to people aged 16 and older who answered yes to the question "during the past 12 months, have you tried to lose weight? About 5% of the sample had joined a weight loss program in the past year.

a. Why do we restrict our analysis to those who answered yes to this question?

b. Below is a subset of some of the other variable included in the survey. questions were asked about actions taken in the past 12 months. Which ones do you believe should be included as covariates? Provide a justistifcation for your choice

AGE

BMI

GENDER

HEIGHT

AVERAGE MINUTES OF EXERCISE PER WEEK

WHETHER THEY TRIED TO EAT LESS CALORIES

WHETHER THEY TRIED TO EAT LESS FAT

WHETHER THEY TRIED TO EAT LESS CARBS