A Manager of a Small Store Wanted to Discourage Shoplifters

question 84

Essay

A manager of a small store wanted to discourage shoplifters by putting signs around the store saying "Shoplifting is a crime!" However, he wanted to make sure this would not result in customers buying less. To test this, he displayed the signs every other Wednesday for 8 weeks, for a total of 4 days displayed. He recorded the store's sales for those four Wednesdays and then recorded the store's sales for the four alternate Wednesdays, when the signs were not displayed. On the Wednesdays with the sign, the sales were 83, 73, 81, and 79. On the Wednesdays without the sign, sales were 84, 90, 82, and 84.
Do these results suggest that customers buy less when the signs are displayed? (Use the .05 significance level.)
a. Use the five steps of hypothesis testing.
b. Sketch the distribution involved.
c. Figure the effect size.
d. Explain what you did to a person who is familiar with the t test for a single sample but is unfamiliar with the t test for independent means.

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Definitions:

Objectivity

The practice of maintaining impartiality and neutrality, avoiding bias or subjective influence in judgments or actions.

Empirical Method

Gaining knowledge through the observation of events, the collection of data, and logical reasoning.

Objectivity

The quality of being impartial or neutral, free from personal bias or emotions, particularly in the analysis or presentation of data.

Science

The use of systematic methods to observe the natural world, including human behavior, and to draw conclusions.