Recall again that Rind & Bordia (1996) investigated whetheror not drawing a happy face
on customers’ checks increased the amount of tips received by awaitress at an upscale
restaurant on a university campus. During the lunch hour a waitressdrew a happy,
smiling face on the checks of a random half of her customers. Theremaining half of the
customers received a check with no drawing (18 points).
The tip percentages for the control group (no happy face) are asfollows:
45% 39% 36% 34% 34% 33% 31% 31% 30% 30% 28%
28% 28% 27% 27% 25% 23% 22% 21% 21% 20% 18%
8%
The tip percentages for the experimental group (happy face) are asfollows:
72% 65% 47% 44% 41% 40% 34% 33% 33% 30% 29%
28% 27% 27% 25% 24% 24% 23% 22% 21% 21% 17%

This time, you are to perform a “hypothesis test” using the tipdata, answering each of
the questions below. For short-answer questions, be brief. However,you must give
enough detail to justify your answers. Single-sentence responseswill generally not
suffice, but do not exceed a paragraph for any given answer.

l. Using the formula discussed in class, calculate Cohen’s deffect size measure.
Provide a brief interpretation of the statistic. Note: simplysaying that the
effect is “small”, “medium”, or “large” will not suffice.