In: Statistics and Probability
You are given the following output for a multiple regression based on a sample of size n = 10
Predictions | Coefficients | Standard Error |
Constant | -0.58762 | |
x1 | b1=1.510 | 0.351 |
x2 | b2=-0.245 | 0.157 |
x3 | b3=1.823 | 0.836 |
SSR=17.56; SSE=8.56
(a) Calculate a 90% confidence interval for β1. Provide a clear interpretation of the interval.
(b) Which predictor variable(s) – x1, x2, x3 – should be kept in the regression model and why, if testing at a 5% level of significance? (use two-sided tests) [If you want, you can provide your answers in a table with 4 rows. In the 1st row, you can set up 6 columns with the headings: Null Hypothesis; For Which Variable; t-Statistic; Critical t-value; Decision; Keep Variable in Equation?. In the other rows, you show your work for variable x1, x2 and x3]
(c) What is the value of the adjusted-R 2 ? Do you think the regression equation fits the data very well?