Hello, I'm struggling to understand the conclusion within the examiners report for this question. Part iii rejects the null hypothesis when the test statistic is -1.96 and compared to t(108, 5%) which gives a critical value of -1.658. However, part iv, despite having the same test statistic, does not reject the null hypothesis when testing at a 'lower' critical value (t108,10%) = -1.2894. I thought the t distribution was also symmetric around zero so unsure why part iii's result rejects the null hypothesis when part iv does not?
On further thought - is this because the question poses a negative beta and we're testing an alternative hypothesis that it is greater than 0 so we would only reject the null hypothesis if the test statistic was greater than 1.2894?
