 Statistics and Excel, Standard Deviation and Variance for a Population Comparing Two Data Sets Related to Weight. Got data? Let's get stuck into it with Statistics and Excel. You're not required to, but if you have access to one note, we're in the icon. Left-hand side, one note presentation, 1467 Standard Deviation and Variance for a Population Comparing Two Data Sets of Weight tab. We're also uploading transcripts so you can go to the View tab, Immersive Reader Tool, change the language if you so choose. Be able to read the transcripts or listen to them in multiple different languages using the timestamps to tie in to the video presentation. One note desktop version here. Data on the left-hand side related to weight in prior presentations. We've been thinking about how to take our data sets, summarize them, represent them in ways so we can draw meaning from that data using both numerical calculations and pictorial representations. Numerical calculations including our standard statistics such as the mean or average, quartile one, the median, quartile three, and so on. And then pictorial representations including the box and whiskers or box plot as well as the histogram. Now we're concerned more with these presentations on the spread of the data. The histogram giving a very nice pictorial representation of that spread. The numerical representation we're working on then being the standard deviation and the variance. So here's our data on the left-hand side. We're mainly focused on the weight information here. Also note that we have not included the entire data set because this was quite a long data set. So we're just giving a snippet of the data set to give an example of the process. Then we're going to do our standard calculations which of course in a very long data set gets quite tedious but using Excel quite easy, calculating the mean or the average, we can just use the average formula, adding up all the data, dividing by the number of data there are, the min, the smallest number in our data set at 7801. We've got quartile one, the middle point of the first quartile, which could be this formula in Excel, quartile.exe, but we have to have the second argument representing quartile one. We've got the second, I'm sorry the first quartile. We've got the median which is the second quartile. We could use the same formula and put a 2 there but it's easier to use the median which will pick up the middle point if we were to summarize the data from top to bottom and pick the one in the middle which again could be quite tedious if you have a very long data set as this one is or is in practice. We snipped it here. Quartile number three, the middle of the third quartile and we have the same formula here except we're now picking quartile number three with the second argument, the maximum, the largest number in our data set at the 170.92. Then we have the standard deviation. This being our point of focus is at the 1166. It's as easy to get in Excel as just putting in the function equals stdev dot p dot p representing the population as opposed to dot s the sample. We're imagining we have all the data for the entire population at this point. We'll talk about samples in future presentation. The variance equals var dot p, similar kind of thing with the p versus the s population versus the sample. And then we've got the standard deviation for the sample just as a comparison note so you can see those two formulas down here. If it was a sample you got the dot s instead of a dot p.