Lopez and Russell (2008) studied y = Rehabilitative Orientation (RO) among a sample of n = 100 juvenile justice workers. Table 8.34 is taken from their Table 8 and summarizes the results of two of their multiple regression models. Model 2 fits two additional independent variables beyond those in Model 1.
(a) For these data, the total SS for y corrected for the mean was 45.778. Calculate SS due to regression model, SSE, and F for each model, and interpret each of the F statistics.
(b) In Model 2, is there significant evidence (at α = 0:05) that type of work is associated with RO? If so, which group appears to have higher expected RO?
(c) Give a 95% confidence interval for the expected difference in RO for two workers with the same values of social support, cultural competency, and employment length, but one in diversion and the other in nondiversion work.
(d) Construct an F test of the null hypothesis that neither type of work nor employment length are associated with RO, after controlling for social support and cultural competency (use α = 5%).