How To Calculate Median

Okay, so now we're going to calculate the median of a set of data. What the median is, it's the middle of the data, so it's a way of looking at the way the data's distributed around the point. So, if we were for example to have a series of values, v1, v2, v3, all the way up to vn minus one, vn, then we would look to find the middle value of that.

To do that, we have to order the data, so we have the lowest first and the highest last, and then we simply count the number of values, and divide that number by two to find the middle value. There'll be questions there about what if we have an odd number of values, and that's what we're about to look at. If we look at our first example here, which is exam score, we have a series of end scores, they've already been ordered, and we have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.

Obviously, halfway between those scores is going to be the sixth and seventh marks. So if we look at that, that's 1, 2, 3, 4, 5, 6 and 7. So we're looking at these two exam scores, and they will tell us simply that the median is 58.

5 because that's halfway between those two scores. So that's for an even number of values, now we're going to example with an odd number of values. What we have here is a selection of heights, again they've been ordered from lowest to highest.

If we count these, we have 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 heights, so the middle value of those 13 heights will be value number 7, and just to show that we have 1, 2, 3, 4, 5, 6 and 7. So this is our median, our median is 170. It's worth pointing out that that's clearly not halfway in between 160 and 192.

That's not what a median means. It's simply the middle value in an ordered set. .