Purchase of fair-trade products. “Just-world” theory proposes that people receive the rewards and/or punishments that they deserve. Marketing researchers examined just-world theory in the context of fair trade (Journal of Marketing, Jan. 2012). In particular, the researchers wanted to know if manipulating the market conditions has an impact on whether consumers would purchase fair-trade products. A designed experiment with two manipulated market factors was employed. One factor was justice reparation potential (low or high); a second factor was producer need (moderate or high). A sample of business students were divided into four groups—34 students were randomly assigned to each of the 2 * 2 = 4 market condition treatments.

After reading a news article and press release that manipulated their condition, students reported on their intention to purchase a fair-trade product. Intention was measured on a scale ranging from 0 to 6 points. The data for all 136 students (simulated based on information provided in the journal article) are saved in the FTRADE file.

An ANOVA for the data is shown in the accompanying MINITAB printout.

a. For this designed experiment, explain (practically)
what it means to have factor interaction.

b. Conduct the F-test for factor interaction using a = .01.
What do you conclude?

c. In the journal article, the researchers reported on the ANOVA F-tests for main effects. Is this necessary?
Explain.

d. A plot of the sample means for the four treatments is shown below in the MINITAB graph. Explain why this graph supports your answer to part b.

e. The researchers hypothesized that when justice restoration potential is low, fair-trade purchase intentions will be lower when need is high rather than moderate.
Conversely, when justice restoration potential is high, purchase intentions will be greater when need is high rather than moderate. Is there evidence to support this theory?

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Analysis of Variance for INT Source DE SS JRP 1 1.360 MS 1.360 F 1.25 P 0.266 NEED 1 JRP*NEED Error 0.622 0.622 0.57 0.451 1 22.405 22.405 20.55 0.000 132 143.948 1.091 Total 135 168.335 S = 1.04428 R-Sq 14.49% - R-Sq (adj) = 12.54%