A mechanistic explanation of popularity. In Exercise 10.59

Chapter , Problem 11.19

(choose chapter or problem)

A mechanistic explanation of popularity. In Exercise 10.59 (page 609) correlations between an adolescents popularity, expression of a serotonin receptor gene, and rule-breaking behaviors were assessed. An additional portion of the analysis looked at the relationship between the gene expression level and popularity, after adjusting for rule-breaking (RB) behaviors. This adjustment was necessary because RB is positively associated both with this gene expression and with popularity in adolescents. The following summarizes these regression analyses using the composite (questionnaire and video) RB score. A total of 202 individuals were included in this analysis. Estimate Standard error Model 1 Gene expression 0.204 0.066 Model 2 Gene expression 0.161 0.066 RB.composite 0.100 0.030 For all analysis use the 0.05 significance level. (a) What are the error degrees of freedom for Model 1 and Model 2? (b) Test the null hypothesis that the serotonin gene receptor coefficient is equal to 0 in Model 1. State the test statistic and P-value. (c) Perform both individual-variable t tests for Model 2. Again state the test statistics and P-values. (d) Is there still a positive relationship between the serotonin gene receptor expression level and popularity after adjusting for RB? If yes, compare the increase in popularity for a unit increase in gene expression (while RB remains unchanged) in the two models. Results such as these suggest not only that adolescents with high serotonin receptor gene expression are predisposed to increased RB behaviors, but also that such behaviors are socially advantageous.