There is some evidence indicating that people with visible tattoos are 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 µ = 4.9, and the distribution of ratings was normal with a standard deviation of s = 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 µ = 4.2.
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 a = .05.
b. Compute Cohen's d to measure the size of the effect.
c. Write a sentence describing the outcome of the hypothesis test and the measure of effect size as it would appear in a research report.