- Kim is organizing a cohort study of young adults in the south bay. She finds that the median income of the enrolled subjects is almost three times more than the median income of the general population of the south bay.

1. What kind of error did Kim just discover?

2. If Kim gets another grant to continue subject enrollment, how might she avoid this issue? - Ben is studying whether exposure to a new high-intensity fitness plan increases the number of pounds a person can lift. He enrolls people in the study and randomly assigns them to the new fitness plan or 30 push-ups a day. After one month, Ben follows up with the people to find out how many pounds they can lift. 1. What type of design is this?

2. Why did Ben randomly assign people to the two different fitness plans? What purpose does that serve?