A study investigated whether men are better at math than women. Twenty randomly selected men took an algebra exam and twenty randomly selected women took a statistics exam. The scores for each exam were calculated. What type of data collection does this represent and what problems do we have?
a) Observational Study; The problem is confounding variables.
b) Experimental Study; The problem is sampling bias.
c) Observational Study; The problem is causation.
d) Experimental Study; The problem is lack of random assignment.
