EXAMPLE 18 Performing the Kruskal-Wallis test using technology

Recall the Chapter 12 Case Study, which investigated whether the amount of information a professor posts about himself or herself (that is, self-disclosure) on the online social network Facebook is related to student motivation.¹⁰ A professor constructed three different Facebook sites: one offering low self-disclosure, one offering medium self-disclosure, and one offering high self-disclosure. Study participants (students not enrolled in the professor's courses) were then randomly and independently assigned to access and browse one of the three Facebook sites, develop an impression of the professor, and complete the research questionnaire. Student motivation was measured using a set of 16 items, and the sum of the 16 items was calculated to form the total motivation score. Use technology and the Kruskal-Wallis test at level of significance to test whether the population median motivation scores are equal for the three types of Facebook pages (low, medium, and high self-disclosure). There were 43 students assigned to the low-disclosure page, 43 assigned to the medium-disclosure page, and 44 assigned to the high-disclosure page.

Solution

Each sample is independent and randomly selected, and there are at least five data values in each sample. Thus, the conditions for the Kruskal-Wallis test are met, and we may proceed with the hypothesis test.