State the type of experiment being conducted in the following situations. In each case, identify the potential threat to internal and external validity.
a. A major distributor of office equipment is considering a new sales presentation program for its salespeople. The largest sales territory is selected, the new program is implemented, and the effect on sales is measured.
b. Procter & Gamble wants to determine if a new package design for Tide is more effective than the current design. Twelve supermarkets are randomly selected in Chicago. In six of them, randomly selected, Tide is sold in the new packaging. In the other six, the detergent is sold in the old package. Sales for both groups of supermarkets are monitored for three months.