Regarding the effect of lifting heavy weights on cholesterol, a group of 54 randomly selected subjects underwent a treatment of selected subjects lifting tennis balls. Researchers who take cholesterol measurements know which participants might experience this and, if so, identify any problems that might cause confounding and explain how they can be avoided.
Identify any issues that may be causing confounding.
Select all that apply
A. The number of groups is very small so there is a possibility of confounding in the selection of group subjects
B. If there is a difference in cholesterol measurements, there is no way to know whether the difference is caused by tre W
C. There may be an experimental effect in this study because the researcher measuring cholesterol will determine which participants lift heavy weights and which participants do not.
D. There is no control group.