 This bootcamp takes you through several mathematical concepts and techniques that you need in order to do the introduction to statistics course. Okay, in this slide you see that the fraction 3 tenths is the same as 0.3, 0.30, and which is also the same as 30%. Okay, to get three tenths, just divide the 10 into 3 and that equals 0.30, so that's how you get a fraction into a decimal, and now if you want to get it as a percentage, take 0.30 times 100%, you get 30%, so these are all equivalent, three tenths, 0.3, 30%. Another measure of variation that we're going to learn when we look at the descriptives lecture in the statistics course is the coefficient of variation. It's a measure of variation that we're going to use for comparing different data sets. And the way we calculate it is converting a fraction to a percentage. We take the standard deviation of the sample S divided by the average, the mean of the sample X bar, and then take that fraction and multiply it by 100%. The coefficient of variation is used to express the standard deviation as a percentage of the mean. So what we do is we're eliminating the units, the standard deviation and the mean are both in the same units as the original data, and when we take this to the fraction, the standard deviation over the mean, we're cancelling the units as well, so we have a pure number, we multiply it by 100%, and that's what we call the coefficient of variation. Example one, the standard deviation was 4 days, the sample mean was 10 days, and the coefficient variation is 4 over 10 times 100% or 40%. In other words, the standard deviation is 40% of the mean. Example two, using the same logic, you can see that the coefficient of variation is 5%. The standard deviation is 5% of the mean. To find more boot camp modules, visit the STAT course at the URL you see there, and go to the navigation bar on the left, click boot camp, and you'll see all kinds of things that are good to do prior to the statistics course. Many of you have already done this before and maybe only need a refresher.