Split Screen is a marketing research company that tests television advertisements. Split Screen has an agreement with a cable television company in a medium-sized city in Iowa. The cable company can send up to four different television ads simultaneously to different households. Split Screen also has agreements with the three of the largest grocery store chains, which will provide scanner data to Split Screen.

About 25% of the residents have Split Screen scan cards that are scanned when items are bought at the grocery store and that allow Split Screen to identify who bought which grocery products. For allowing Split Screen access to their television hookups and their grocery purchase information, residents receive bonus points that can be used to buy products in a special points catalog. Identify and diagram the true experimental design possible using the Split Screen system. Assess the internal and external validity of Split Screen's system.