A study was conducted to determine whether amounts of tips left for  servers are affected by giving guests free candy along with the bill. Four different groups were used: (1) No candy, (2) one piece of candy, (3) two pieces of candy, (4) the offer of an additional piece of candy after the customer selected one piece of candy. The results of analysis of variance are shown in the accompanying Excel display (based on data from “ the Till: The Use of Candy to Increase Restaurant Tipping,” by Strohmetz et al., Journal of Applied Social Psychology.

Use a 0.05 significance level to test the claim that tip amounts are affected by giving guests candy.

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Excel ANOVA Source of Variation Between Groups Within Groups Total SS 207.0906 338.4416 545.5322 df MS F 3 69.0302 15.50133 76 4.453179 79 P-value F crit 5.84E-08 2.724944