A sociologist interested in salesperson-consumer interaction wanted to know if customers really are influenced to buy more from sales clerks who smile. To test this, clerks at eight stores in a large Canadian clothing chain were given special instructions at the start of a week, and the number of sales over the week were recorded. Four of the stores were randomly selected to have the clerks receive instructions to be especially courteous and to smile a lot. Clerks at four other stores were simply instructed to be especially courteous. Sales (in thousands of dollars) for the four stores in the smile condition were 36, 40, 36, and 44; sales for the four stores in the control condition were 40, 31, 27, and 30. Do these results suggest that customers might buy more if they encounter smiling sales clerks? (Use the .05 level.) a. Use the five steps of hypothesis testing.
b. Figure the effect size.