Donald Heel is the Microwave Oven Division Manager of Sharp Products. Don proposes a $50 cash rebate program as a means of promoting Sharp’s new crisp-broil-and-grill microwave oven. However, the Sharp president wants evidence that the program would increase sales by at least 25%, so Don applies some of his research budget to a survey. He uses the National Phone Systems Company to conduct a nationwide survey using random digit dialing.

National Phone Systems is a fully integrated telephone polling company that is capable of providing daily tabulations. Don decides to use this option, and instead of specifying a final sample size, he chooses to have National Phone Systems perform 50 completions each day. At the end of five days of fieldwork, the daily results are as follows:

For how much longer should Don continue the survey?
Indicate your rationale.

Transcribed Image Text:

Day Total sample size Percentage of respondents who would consider buying a Sharp microwave with a $50 rebate 1 50 2 3 100 150 35% 50% 40% 4 5 200 250 30% 33%