Question 9.17

9.17 To tip or not to tip.

A study of tipping behaviors examined the relationship between the color of the shirt worn by the server and whether or not the customer left a tip.8 Here are the data for 418 male customers who participated in the study.

tipmale

Shirt color
Tip Black White Red Yellow Blue Green
Yes 22 25 40 31 25 27
No 49 43 29 41 42 43
  1. Use numerical summaries to describe the data. Give a justification for the summaries that you choose.
  2. State appropriate null and alternative hypotheses for this setting.
  3. Give the results of the significance test for these data. Be sure to include the test statistic, the degrees of freedom, and the P-value.
  4. Make a mosaic plot if you have the needed software.
  5. Write a short summary of what you have found including your conclusion.

9.17

(a) Answers will vary. The percent that tip for each shirt color are Black 30.99%, White 36.76%, Red 57.97%, Yellow 43.06%, Blue 37.31%, Green 38.57%.
(b) There is no association between whether a male customer tips and shirt color of the server. There is an association between whether a male customer tips and shirt color of the server.
(c) .
(e) The data provide evidence of an association between whether or not the male customer left a tip and shirt color worn by the server. Red-shirted servers got the most tips!