Chapter 8, Problem 12P

There is some evidence indicating that people with visible tattoos ore viewed more negatively than people without visible tattoos (Resenhoeft, Villa, & Wiseman. 2008). In a similar study, a researcher first obtained overall ratings of attractiveness for a woman with no tattoos shown in a color photograph, On a 7-point scale, the woman received an average rating of $\mu$ = 4.9, and the distribution of ratings was normal with a standard deviation of $\sigma$ = 0.84. The researcher then modified the photo by adding a tattoo of a butterfly on the woman's left arm. The modified photo was then shown to a sample of n = 16 students at a local community college and the students used the same 7-point scale to rate the attractiveness of the woman the average score for the photo with the tattoo was M = 4.2.

1. a. Do the data indicate a significant difference in rated attractiveness when the woman appeared to have a tattoo? Use a two-tailed test with $\alpha$ = .05
2. b. Compute Cohen's d to measure the size of the effect.
3. c. Write a sentence describing the outcome of the hypothesis test and the measure of effect sire as it would appear in a research report.