Q.5 Does your answer to the previous question mean that Original/Repeat loan status is the root cause of an expected improved PRSM score or might there be another explanation? If so, suggest a possible "lurking" variable that could influence the comparison (the lurking variable can be a hypothetical one, it doesn't have to exist in the data set). Otherwise, explain briefly why it is not possible. (Reading Section 5.2 of Stine and Foster could be helpful here.)