Given below are results from the regression analysis on 40 observations where the dependent variable is the number of weeks a worker is unemployed due to a layoff (Y) and the independent variables are the age of the worker (X1), the number of years of education received (X2), the number of years at the previous job (X3), a dummy variable for marital status (X4: 1 = married, 0 = otherwise), a dummy variable for head of household (X5: 1 = yes, 0 = no) and a dummy variable for management position (X6: 1 = yes, 0 = no). The coefficient of multiple determination (R 2 j ) for the regression model using each of the 6 variables Xj as the dependent variable and all other X variables as independent variables are, respectively, 0.2628, 0.1240, 0.2404, 0.3510, 0.3342 and 0.0993. The partial results from best-subset regression are given below: Model R Square Adj. R Square Std. Error X1X5X6 0.4568 0.4116 18.3534 X1X2X5X6 0.4697 0.4091 18.3919 X1X3X5X6 0.4691 0.4084 18.4023 X1X2X3X5X6 0.4877 0.4123 18.3416 X1X2X3X4X5X6 0.4949 0.4030 18.4861

46) True or False: The model that includes X1, X5 and X6 should be selected using the adjusted r2 statistic.

47.)True or False: The sampling error can either be positive or negative.

48) True or False: A sample is used to obtain a 95% confidence interval for the mean of a population. The confidence interval goes from 15 to 19. If the same sample had been used to test the null hypothesis that the mean of the population is equal to 20 versus the alternative hypothesis that the mean of the population differs from 20, the null hypothesis could be rejected at a level of significance of 0.05.