Table 1 Does red increase mens attraction to women?
A recent study1 examines the impact of the color red on how attractive men perceive women to be. In the study, men were randomly divided into two groups and were asked to rate the attractiveness of women on a scale of 1 (not at all attractive) to 9 (extremely attractive). Men in one group were shown pictures of women on a white background while the men in the other group were shown the same pictures of women on a red background. The results are shown in Table 1 and the data for both groups are reasonably symmetric with no outliers. Table 1 Does red increase men\'s attraction to women? To determine the possible effect size of the red background over the white, find a 90% confidence interval for the difference in mean attractiveness rating mu Subscript Upper R Baseline minus mu Subscript Upper W , where mu Subscript Upper R represents the mean rating with the red background and mu Subscript Upper W represents the mean rating with the white background.
The degree of freedom= n1+n2-2= 15+12-2 =25
Given a=1-0.9=0.1, t(0.05, df=25) =1.71 (from student t table)
So the lower bound is
(xbar1-xbar2)- 2*sqrt(s1^2/n1+s2^2)
=(7.2-6.1)-1.71*sqrt(0.6^2/15+0.4^2/12)
=0.7695966
So the upper bound is
(xbar1-xbar2)+ 2*sqrt(s1^2/n1+s2^2)
=(7.2-6.1)+1.71*sqrt(0.6^2/15+0.4^2/12)
=1.430403