How do you find the t*?

To find the t∗ use Excel’s T.INV formula, start by converting the confidence interval to a cumulative probability. This requires identifying the percentage in each tail of the distribution. For example, for a 95% confidence level, there’s 5% remaining for both tails (2.5% in each tail). To find the cumulative probability up to the upper bound, add 95% and 2.5%, resulting in 97.5% (or 0.975). This is the probability you’ll enter into the formula, along with the degrees of freedom(n−1). For instance, with 24 degrees of freedom, you would use =T.INV(0.975, 24), giving you t*