13. Hypothesis testing against two-sided alternative using the t-statistic
Suppose a data set of 400 observations (N = 400) was analyzed using OLS to examine the relationship between rent and student population in college cities. The regression results are as follows, with standard errors in parentheses:
log(rent) = log(pop) - 0.007 pctstu + 0.6 log(avginc) (0.99) (0.02)
where:
- rent is the average monthly rent
- pop is the total city population
- avginc is the average income of city residents
- pctstu is the percentage of city population who are students
Based on the number of observations and parameters in the model, there are degrees of freedom.
Suppose you want to test the null hypothesis that student population has no ceteris paribus effect on monthly rent in college cities. Since you are using the null hypothesis, your t-statistic is 0.007 / 0.003 = 2.333.
For the two-sided alternative hypothesis, with a 5% rejection rule (i.e., at the 5% level), you should compare the statistic to the critical value. In this situation, you would reject the null hypothesis if the t-statistic is greater than the critical value of 2 or less than -2.