When you get a surprisingly low price on a product do you assume that you got a really good deal or that you bought a low-quality product? Research indicates that you are more likely to associate low price and low quality if someone else makes the purchase rather than yourself (Yan & Sengupta, 2011). In a similar study, n = 16 participants were asked to rate the quality of low-priced items under two scenarios: purchased by a friend or purchased yourself. The results produced a mean difference of M_D = 2.6 and SS = 135, with self-purchases rated higher.

a. Is the judged quality of objects significantly different for self-purchases than for purchases made by others? Use a two-tailed test with = .05.

b. Compute Cohen's d to measure the size of the treatment effect.