1. A sample of 12 observations collected in a multiple regression study on two independent variables (X1 and X2) shows the following partial results. SST = 12321 and SSE = 3516. If SSR(X1) = 4496 and SSR(X2) = 5378, what statistical decision should be made (at the 5% level of significance) when testing the null hypothesis that variable X1 does not significantly improve the model after variable X2 has been included? a. Reject the null hypothesis. b. Do not reject the null hypothesis. c. Reject the alternative hypothesis. d. Accept the null hypothesis. 2. When testing the null hypothesis of no positive autocorrelation, you neither reject nor not reject the null hypothesis if a. the Durbin-Watson statistic is greater than dL b. the Durbin-Watson statistic is less than dL c. the Durbin-Watson statistic is between dLand dU d. the Durbin-Watson statistic is greater than dU