12.30. A study5 described an experiment that randomly assigned participants to receive $3 to spend on themselves

(self-interest), or to receive $3 to donate to a nonprofit charity (imposed charity), or to receive $3 that they could either spend on themselves or donate to charity (choice).

After receiving or donating the money, the participants rated how happy they were with this experience, on a seven-point scale (with 1 = not at all, 7 = an extreme amount). The authors reported a significant effect (F =

9.08, P < 0.001), with follow-up t-tests confirming their hypothesis that imposing self-interest increases outcome happiness. For their analysis, identify the response variable, the explanatory factor, and the hypothesis tested to yield the reported F statistic and P-value.