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You just started a job as the only health promotion specialist at Google-Ann Arbor. The top priority of management is a weight-control program for its new employees. They want to try out a 6-month “lifestyle change” program on 200 individuals in the Ann Arbor office. Your new boss is eager to do what she calls a “scientific” study of the weight-management program and tells you that she has already arranged for you to collect baseline and follow-up data on 200 employees in their Mountain View, CA facility so that you have a comparison group. In other words, the design she suggests looks like this:

O1 X O3

——————–

O2 O4

a. Name the major threat to the internal validity of this design. Explain your answer.

b. Suggest an alternative design. Describe and explain your revision to the original design. Please explain one limitation to your design in terms of internal validity.