Answer Happy

Does a positive message written on a bill increase the tip received by a waiter? Researchers gave 60 index cards for a waiter at an Italian bistro in New Jersey. Each card had one of three messages written on it: - Good: "The weather is supposed to be really good tomorrow. I hope you enjoy the day!" - Bad: "The weather is supposed to be not so good tomorrow. I hope you enjoy the days anyway!" - None: No message. Before delivering a bill to customers, the waiter randomly selected a card and wrote the chosen message on the bill. The researcher obtained the following computer output. Message N Bad 20 Good None 20 Mean 18.180 22.220 18.725 StDev 2.098 1.959 2.388 20 P-Value Analysis of Variance Source DF SS MS F-Value Report 2 192.2 96.112 Error 57 264.9 4.648 Total 59 457.1 Where MS means mean square. The statistic and p-value have been purposefully erased. Histograms of the percent tip for each message. a) Define all relevant parameters and write the null and alternative hypotheses. b) Check conditions for inference. c) Calculate F. (Hint: F = MSG / MSE, and both MSG and MSE are given in the computer output.) d) Use the F distribution on StatKey to determine a p-value. e) What is your conclusion to the hypothesis test?

Histograms of the percent tip for each message. Dotplot Histogram Box plot None Bad Good 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0