Hi and welcome back. This is the last lesson about confidence intervals. We are not going to get too deep into it as it is just about knowing the formula. Sometimes we want to find the confidence interval for two sample means where the samples are independent with unknown variances and the variances are assumed to be different. You can think about comparing apples and oranges. You've heard the expression right. Well in statistics if you actually want to compare apples and oranges This is the right way to do it. Here's the confidence interval formula. Once again we have the differences of the means of the two samples the variances or the sample variances of each of the two variables. And here are the respective sample sizes. The tough thing about this is to estimate the degrees of freedom well. Statisticians have come up with a formula that allows us to do just that. You have all the information but it is
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