Say youre going to conduct a t procedure for the difference between the means of two populations. You decide the samples of sizes 12 and 15 are independent. Which of the following statements are true?
1. If we pool variances the number of degrees of freedom is 25.
2. If we don't pool and we don't have access to software to compute the degrees of freedom the number of degrees of freedom is 11.
3. For a given level of confidence c a confidence interval based on 11 degrees of freedom will be wider than one based on 25 degrees of freedom.