 So we can also represent data in statistics using a variety of charts. And the simplest is a bar chart, and this is because sometimes it's hard to read numbers, and so will represent them using pictures. And all statistical charts, no matter what they are, are ultimately based on the unit concept. In a bar chart or a histogram, the magnitude of a quantity is going to be represented by the length of a bar, just as the length of a tape corresponds to the value of a number. So for example, let's say I have the grade distribution of grades in a class, and maybe it looks something like this. So for those who get A, there's 7, 9B, 6C, and so on. And so let's go ahead and construct a bar chart for the data, and we'll start off by finding the bars themselves. So we'll need to decide on how big we're going to make each bar. And the reality is that if it really matters, you're going to be using technology to produce an accurate bar chart. So the value of constructing a bar chart by hand is very minimal, and it's primarily done so that when you look at a bar chart, because you know how the bar chart is created, it is easier to understand what the bar chart tells you. So to create the bar chart by hand, we'll use two important guidelines. First one is free. However big we decide our units to be doesn't matter. Make it whatever size you want to. You will have to work with it later, so that's an important consideration, but it doesn't make a difference how big that first bar is. But you do want to maintain relative size. And what that means is that once you've decided how big the first one is, then consistency counts. Larger amounts should be represented by longer bars. So for example, the first category has seven students, so I'll draw a bar of random length. It doesn't really matter what it is. I'll draw it. My second category has nine students, and I have to think nine is more than seven. So the bar should be longer than the one representing seven students. So I'll draw a somewhat longer bar. And the third category has six students. That's fewer students than seven, so the bar should be shorter. One student, much less than either six or seven, so I do want to draw an even shorter bar. And finally, this last bar representing two. Well, that's more than one, so it should be longer than this. It's less than six, so it should be smaller than six. So maybe I'll draw something like that. And then I'm going to collect and label. Label is important. If it's not labeled, it doesn't mean anything. And I'm going to collect and label to form the chart. So I'll take my A bar, label it A, my B bar, label it B, C, D, and F. And importantly, the bar chart can go in either a horizontal orientation like this, or we can also run it vertically like that. So either way is acceptable as a bar chart. There really isn't any distinction between the two of them.