Here I'm going to show you how to use some time series data, to create a line chart. And I'm also going to do some calculations that will allow you to use these data a little more effectively, something called a percentage change. Here I have data from 1947 through 2016 for the consumer price index. These data were downloaded from the Federal Reserve Economic database at the St. Louis Fed. Now, if I highlight some of the information here, right, let's say 1947 through 1957. And I insert a line chart like this, I might get some very interesting information here, I'm going to move this chart, oops. Let's move this chart over to a new chart. Okay, and you will notice that I have got all this blank space here. I have got some very nice information over here but with all of these blank space. So what I want to do is I want to charge the access, all right? Down here if I click on the access, I can then format the access so that I have different pieces of information. In this case what it does is it has a lower bound of zero, which is like 1900, I do not want that, okay? So I could change this to, let's say, 15, like that, which allows me to sort of move it closer to the here. Now I'm starting in 1941. Or I could change it to 1800, let's say, like that, okay? Now I've got 1947, I change to 1600, right? Now it's starts in 1943. And so now the data are a little bit more in terms of the x-axis here. I'm really getting a much better picture instead of having all of this blank space, all right? And I also might want to change the y-axis. Like here, again, I have all of this blank space, and the more blank space doesn't highlight like all the big changes that might be occurring here. And so here I can highlight this axis and in the minimum I might want to start at, let's say, 20. So if I type in 20 here, it then starts the axis at 20 and moves up to 29. Now what I can do is I can see all of the big changes that are occurring, okay? One of the things that I see over and over again with students, people who are presenting is that they don't change the axis. They leave the scales in very strange situations so that you're looking at the data from like 30,000 foot. So then you're missing all the little movements, all the micro bombs, all the sort of little changes that are occurring that would allow you to better assess what's going on that information, how do I interpret it? Is it telling a different kind of a story? So by looking at it from a 30,000 foot, you might not see all of the changes that are really taking place. Or you might not see that the changes look meaningful. In this case, when we zoom in on it, we can see that there's little nooks and crannies, little bumps and what have you. In these data that might tell a little bit different story than if we were looking at it from really, really, really, really far back. So, finding the appropriate chart is really valuable. But also, making sure that you're focusing in on the information, change the axis, change your scales, make sure that they're focusing on the data, so that you can tell the compelling story that you need to tell. Here, we're going to look at this same data, but instead of just looking at the CPI, what we're going to do is, we're going to calculate this thing called a percentage change. And so in this, I am going to do a year over year percentage change. Now year over year of percentage change says that I'm going to take the information in the current year, so I'll say like, let's take information from January 1948 and compare it to January 1947 as a ratio of January 1947. So, what I'm doing is saying the new minus old as a ratio of old. So, how much has CPI changed since the same month the previous year? Okay, and then what I can do is I can turn this into a percentage. Now I'm going to, so I'm going to scroll this down for a couple ten years here. All the way through like, say, 1958. Now what I have here in this axis is how much has the CPI changed over the course of one year? All right, in this case, I am looking at slightly different information. And so here, I might actually want to use like, let's say, a bar chart. Okay, and so, I'm using a bar chart here, let's move this chart into a much larger sheet. It's telling me, okay, here is the length. The height here is the percentage change in CPI, turns out to be something called inflation, I'm sure you're familiar with it, right? So now I know when we have really high inflation, when the height of the bar is going up. And I also know when we have deflation. Now I might have to change this axis over here. So, I'm going to select the data and I'm going to add information about the y-axis down here so that we basically have the years and the months. Let's insert, A row here and we're going to take this information right here and copy it over, so that we have those data available to us. Now what I'm going to do is I'm going to highlight both the data and the percentage change, which is now my inflation. And I'm going to insert my bar chart here. And remove this to a much larger chart. So now I have the same information here. The height of my bar is the percentage change in CPI, which is the inflation. And my dates are along the x-axis here. So I say, okay, look, I can tell right here when we've had deflation. I can tell right here when we've had deflation. And then this gives your presentation, or the ability for your viewer, your reader, to say, what's happening during this period of time? What's happening during this period of time? All right, in this case, the bar chart is much more effective than, lets say, a scatter plot. The bar chart is much more effective than, let's say, even a line graph, because we can sort of see what's going on each of these quarters. It's very compelling. All right, the goal of using data and figures, or graphs, or charts, is not just to create the fanciest thing that you can, it's very, very easy to do and it's very easy to go overboard with Excel. The real goal should be for you as the presenter, to make your information available to the reader in a way that allows you to tell very compelling story, a very effective story. And so this is what people want to see, a picture is worth 1,000 words. If you do it correctly, you can make your point very quickly and very easily. And maybe convince somebody that organization should be changing its policy. Or you're telling a compelling story about what's happening within organization, or in this case, some historical information about the economy.
