In this video, I want to show you how to do simple descriptive statistics. We're going to look at measures of central tendency and measures of dispersion. Look on the left-hand side here. I've got two variables, Variable 1 and Variable 2, they both seem to be continuous numerical values. We might imagine that this is the blood results for a group of patients. This is blood test number one and blood test number two, and for 30 patients, we've recorded the values for each of these blood tests. I want to show you the quick and easy way of getting all of our descriptive statistics in one go. Now we see in the first cell, A1, and the first cell, B1A, we have the variable names and the actual values only start in A2 and B2. So, we're going to go to data, we're going to go to data analysis and we're just want some descriptive statistics. There we go. Now the range, I've already folded in, it's A2 to B31. Remember, that's 82 there all the way down across and down to B51. That's going to be all the values. I want the upward range to be here in cell D number 2, so I've clicked there. Now this is the second time I'm running it, so it'll have these little dollar sign, so you can just click a name, type D2. You can just click and type in A2 colon B31. We want summary statistics please. We want the confidence intervals as well, and we're going to have a video on how to do confidence intervals, but let's do this part of the descriptive statistics that's not available in the libre office suite. But let's do it here anyway and we're going to click OK, and voila, there we go. Now, it's not going to call it variable1 and variable2 here on the macros, it calls it Column1 and Column2 for these two columns. And we can see for each column, we get the mean, the standard error, the median, the mode, the standard deviation, the sample variance, the ketosis, the sequinous, the range, the minimum and maximum, the sum, the count, and a 95% confidence level all in one simple easy go. But, I also want to show you how to do this, just using functions. These are the values we want to calculate. We're going to calculate mean median mode, sample [INAUDIBLE], sample variance, sample size, standard error Minimum, maximum, range, first quartile, second quartile, remember that's the median. Third quartile, remember also the zero quartile would actually be the minimum, and the fourth quartile would be the maximum. And then calculating the interquartile range, which we don't see yet on the side. Mean is very simple, we can do type in = average, it comes up there, and it just wants the list of values. So we're going to do variable 1 on it's own, and it starts at A2 and it goes all the way to A31. And there we go, 46.6 and what did we get on this side, 46.6. The median, you have guessed it, equals median. There we go, I can select it and again, we're going from A2 to A31. There we go, 45.5 so a bit of a difference between the median And the mean. Let's go for mode. You'll see in newer versions, there are two types of modes, multi and single, in case you have more than one value that occurs commonly So let's select that. Instead of typing in A2-A32 I can just click, hold, and drag all the way down, and that will be filled in for me. A2-A31. We hit Return, or the little checkmark, that's done. Let's do the sample standard deviation =STDEV, but there's a .P and a .S. P is for the whole population and S is for sample. The equations are slightly different so let's choose sample, these are just samples of patients and a A2 to A31. There we go. The sample variance, again, we will get .P and .S. We want sample, so .S A2 to A31. There we go, the sample size is the count function, and let's count. That's quite easy to do, you can do it in your head, but let's do it. A2 to A31, and then we get a sample size of 30. Now, we are going to discuss standard error in future lectures, and I'll also show you how to do that. It's part of calculating the confidence intervals. But it's simply equal To the sample standard deviation. So, I say equals and I click on that cell that falls in J5, which is the value that is held in the cell, divided by the square root which is SQRT, that is the function. And the square root of the sample size. Instead of typing in 50, I can click on that 50. And you see we have relative cell references to those values. I hit enter and we see a standard error. Minimum is m-i-n, simple as that. A2 to A31, so the minimum value is 31. And the maximum value, max, simple as that, 822831, until I find the maximum value which was 60. Now the range remember that is just the maximum minus the minimum. So I say equal and I click on the maximum value minus and I click on the minimum value and I hit Enter And we see the range is 29, just as we saw on this side, 29. The first quartile. Well, we have a function called quartile. Q-U-A-R-T-I-L-E. And we want the inclusive one. We want all the values to be included. It asks for two arguments. The array and the quartile. So the array. This is simply a fancy word for this list of values, comma, sometimes on the Mac OS, depending how your system is set up you might require a semicolon. One, we want the first quartile. The second quartile is second the median so let's see if it does come out as the median. .inc. We want A2 to A31 comma, the second quartile. And indeed, it's the same as the median. Let's do the third quartile. Quartile. Let's select there. It is A2 to A31 Comma the third quartile. There we go. And lastly, the inter-quartile. Just remember that's equal the value of the third quartile. So I click in there minus the first quartile and I click in there and we have the inter-quartile range. Now that was a lot of typing and selection et cetera. There's an easy way for me to do this Fortunately, we've typed it in that these two are right next to each other. And these little cell references that we're referring to when we select A2 to A31, these are called cell references, but they are not fixed in place. It actually does not say A2 when I type it in. It says, from where I am now, where I type in A2 Go to A2 and it finds a root. Now the easiest root is 1, 2, 3, 4, 5, 6, 7, 8, 9, cells to the left. That is what Excel sees, it does not see A2 for the. It sees Go left nine places from where I'm typing this and then go down so many places to the bottom. So look at this magic. If I were to select all of these, click + hold and drag all the way down. Let go. I'm going to go over to the bottom right hand corner. My cursor changes. I'm going to click + hold and drag across to this side and let go. And there we are. All the values are filled in. Now look at the magic. Let's send A2 to A31. Look there in the bar. A2 to A31 if I click it. It actually highlights what it selected. Hit escape because I don't want to change anything. If I click in this one. Look at that is now B2 to B31. So it also just went across nine cells. It is a relative reference not the actual value. It's the relative. It says go to the left nine cells. And when I dragged it across to the cell towards to the right. It still goes nine places to the left which now becomes This value here, so in one go I could do all of those values. So quick and easy how to do descriptive statistics on Data 6, either doing it automatically here with a data analysis toolpack. Or doing it through functions by hand.
