How to Use Excel's TTEST Function

Video Transcript

"Hi, my name's Dave Andrews and I'm going to show you how to use Excel's TTEST function. The TTEST function is used for statistical analysis of data cells. Let's open Excel, and I already have a spread sheet here. It shows a list of people, how much they weigh, and lets say they went through a dietary test and it shows how much they weighed after their diet. It also has the average of their weights, before and after the diet. Now, what the TTEST function will do, in this case, is it's going to compare each one of these items. It's going to tell us whether or not the diet actual made a statistical difference in the people's weights on a consistent basis. Let's come down here. Let's click on formulas. We're going to insert a statistical function. Let's select TTEST. This opens up the arguments screen that lets you select the arguments with a function. For array one, that's your first data set, I'm going to select all of the data in the B field, except for the average. For array two, we'll select all the data in the C field. The tails is going to be the type of test that it's going to do which is a type of distribution. We're going to do a two tail distribution, so we're going to use two. The three, oh for type, rather, you have several different types of tests that you're going to run. The one we want to run is a two sample unequal variance. So, let's type in three as the type. Tails should actually be one 'cause we're doing a two sample equal variance and say okay. As you can see, this is the statistical result of the two test variable and it's around five percent which is typically within a margin of error for statistical analysis. What this is saying is that since there's only a five percent margin of error for these differences, it's a good chance that the diet that these people went through made a significant impact upon their weight. My name is Dave Andrews and I've just showed you how to use a TTEST function in Excel."