A direct-mail retailer experimented with three different ways of incorporating order forms...

A direct-mail retailer experimented with three different ways of incorporating order forms into its catalog. In type 1 catalogs, the form was at the end of the catalog; in type 2, it was in the middle; and in type 3, there were forms both in the middle and at the end. Each form was sent to a sample of 1,000 potential customers, none of whom had previously bought from the retailer. A code on each form allowed the retailer to determine which type it was; the number of orders received on each type of form was recorded. Excel was used to calculate expected frequencies and the χ2 statistic. Excel's CHITEST function gave the p-value. The results are shown here.

a. What does the null hypothesis of statistical independence indicate about the three types of order forms?

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b. Can this null hypothesis be retained at normal α levels?