In a recent study, Piff, Kraus, Cote, Cheng, and Keitner (2010) found that people from lower social economic classes tend to display greater prosocial behavior than their higher class counterparts. In one part of the study, participants played a game with an anonymous partner.
Part of the game involved sharing points with the partner. The lower economic class participants were significantly more generous with their points compared with the upper class individuals. Results similar to those found in the study, show that n = 12 lower class participants shared an average of M = 5.2 points with SS = 11.91, compared to an average of M = 4.3 with SS = 9.21 for the n = 12 upper class participants.
a. Are the data sufficient to conclude that there is a significant mean difference between the two economic populations? Use a two-tailed test with a = .05.
b. Construct an 80% confidence interval to estimate the size of the population mean difference.