Question 14.67

14.67 Word-of-mouth communications.

Consumers often seek opinions on products from other consumers. These word-of-mouth communications are considered valuable because they are thought to be less biased toward the product and more likely to contain negative information. What makes certain opinions with negative information more credible than others? A group of researchers think it may have to do with the use of dispreferred markers. Dispreferred markers indicate that the communicator has just said, or is about to say, something unpleasant or negative. To investigate this they recruited 257 subjects and randomly assigned them to three groups: positive-only review, balanced review, and balanced review with a dispreferred marker. Each subject read about two friends discussing one of their cars. The positive-only group heard that it has been owned for three years, rides well, and gets good gas mileage. The other two groups also hear that the radio and air conditioner cannot run at the same time.17 One of the variables measured is the credibility of the friend describing her car. Here is part of the ANOVA table for these data:

Source Degrees of
freedom		 Sum of
squares		 Mean
square
Groups 183.59
Error 2643.53
Total 256
  1. Fill in the missing entries in the ANOVA table.
  2. State and for this experiment.
  3. What is the distribution of the statistic under the assumption that is true? Using Table E, give an approximate -value for the ANOVA test. Write a brief conclusion.
  4. What is , the estimate of the within-group variance? What is the pooled standard error ?

14.67

(a) . (b) : not all of the are equal. (c) . There are significant differences among the groups. (d) .