13.25 The effect of humor. In advertising, humor is often used to overcome sales resistance and stimulate customer purchase behavior. One experiment looked at the use of humor to offset the negative feelings often associated with website encounters.¹⁷ The setting of the experiment was an online travel agency, and the researchers used a three-factor design, each factor with two levels. The factors were humor (used, not used), process (favorable, unfavorable), and outcome (favorable, unfavorable). For the humor condition, cartoons and jokes of the day about skiing were presented on the site. For the no humor condition, standard pictures of ski sites were used. Two hundred and forty-one business students from a large Dutch university participated in the experiment. Each was randomly assigned to one of the eight treatment conditions. The students were asked to book a skiing holiday and then rate their perceived enjoyment and satisfaction with the process. All responses were measured on a seven-point Likert scale. A summary of the results for satisfaction follows:

Treatment	n		s
No humor—favorable process—unfavorable outcome	27	3.04	0.79
No humor—favorable process—favorable outcome	29	5.36	0.47
No humor—unfavorable process—unfavorable outcome	26	2.84	0.59
No humor—unfavorable process—favorable outcome	31	3.08	0.59
Humor—favorable process—unfavorable outcome	32	5.06	0.59
Humor—favorable process—favorable outcome	30	5.55	0.65
Humor—unfavorable process—unfavorable outcome	36	1.95	0.52
Humor—unfavorable process—favorable outcome	30	3.27	0.71

(a) Plot the means of the four treatments without humor. Do you think there is an interaction? If yes, describe the interaction in terms of the process and outcome factors.
(b) Plot the means of the four treatments that used humor. Do you think there is an interaction? If yes, describe the interaction in terms of the process and outcome factors.
(c) The three-factor interaction can be assessed by looking at the two interaction plots created in parts (a) and (b). If the relationship between process and outcome is different across the two humor conditions, there is evidence of an interaction among all three factors. Do you think there is a three-factor interaction? Explain your answer.