Additional Counting Plots Video Lecture Transcript
This transcript was automatically generated by Zoom, so there may be discrepancies between the video and the text.

0:00:00
Hi everybody, welcome back. In this video we're going to look at some additional basic counting plots. So these are things we haven't covered before. These are going to be two new plot types that we can make in Tableau pretty quickly. So these are going to be unit charts and bubble charts. So a unit chart is a very simple icon repeated the number of times for each category. So for instance here, this is the unit chart we're going to make for the different species, I believe, of penguin. So each square here will represent a penguin and then the colors provide us, tell us the type of penguin and then the number of each color tell us the number of that type of penguin. So let's go ahead and dive into Tableau.

0:00:43
We're working again with this penguins data set that we've been working with the past two videos. How do we make a unit chart? So the first thing we need to go do is to analysis and get rid of aggregate measures. And then the next thing we're going to do is go to species and then drag it to color. And so now you can see we've got our unit chart here. It looks a little bit different. So we can get it closer to the one so like you can change the width of your visualization. You can also change the size. So changing the size of the squares also changes the visualization as you can see. But that's it. We can also, if we wanted to, we could go to do the species and make it, so currently it's automatic, but if we changed it to shape, then we could make the species also do the shape. So if you wanted it to be both the color and the shape, maybe for people who have a difficult time seeing the differences in color, and we could go to the filled versions if we prefer that. So, Adelaide can be circle, Chinstrap can be square, and Gintu can be the filled in. Let's go with diamond. Okay, and so now we see the difference.

0:02:01
This is also a valid unit chart where if instead of doing just the color, you wanted to do the marker type, that's also OK. OK, so that's a unit chart. Let's talk before we move on to the next chart type. Let's go back to our slides. So we showed how to make unit charts in Tableau. So here are some general unit charts for some notes. So this isn't a common go-to for making visualization. It exhibits something called the moire effect, which as you can see if you like look at it too closely you can see sort of like almost a vibration happening where the solid colors, the colors themselves are just too close to one another so you can kind of see them almost bleed into one another and give the sense of the image vibrating which is both kind of hard on the eyes and makes it unpleasurable to look at.

0:02:54
But this can be used as sort of a statement visualization that can connect more with your audience. So, here you'll see an example of a unit chart made by the New York Times when they were trying to visualize the COVID death count at this point in time. So, each point here was representing someone who passed away from COVID-19. And then you can kind of get the effect of the sheer number of people who passed away based on the number of marks. So unit charts are not a common go-to, but they can be a nice statement piece for your visualization. The next type of chart we're going to look at is called a bubble chart.

0:03:33
So these are plots where you have circles or other shapes where the area of that shape is equal to the total observations represented. So let's go ahead and make a second sheet, and this is leftover from the last video I made, so let's get rid of that real quick. So in this one, instead of having aggregate measures off, we want aggregate measures to be on, and what we're going to pull over species into the color mark, and what we're going to also pull it over into the size mark, and we're going to change these from dimensions to measures, and we're going to count them. So now in the count on the size, you can see we have these different measures, these different circles, whose size is now proportionate to the number of penguins.

0:04:25
Then we can go ahead and add, if we'd like to add labels to it, we can also add a label to the different ones. So this will add a nice label. And I wonder if we can edit it. Let's see what happens if we click on this. I believe we can increase the font size maybe to 15 to make it a little easier to read. So this is a bubble chart. Bubbles because we have circles. I believe we could also do like squares if we wanted, although this is technically called a tree map, which we'll learn about later. So let's stick, instead of trying to mix it up, I'm going to go ahead and go back to the circle because this is the bubble chart. We'll learn more about that square visualization I made in a later video.

0:05:14
Okay, so let's go back. This is a really straightforward chart to make in Tableau and we've made it. So let's go back and talk about bubble charts in general. So you wanna be careful when making any plot where you're using area, which is a two-dimensional unit, right? So r squared, pi r squared is the area formula for a circle. You wanna be careful when you use area, which is a two-dimensional unit, to make comparisons of a one-dimensional unit.

0:05:41
So here, the unit we're choosing is the number of penguins, and we're using a two-dimensional unit to compare. So you want to make sure that it's the area of the circles that's equal to the metric, and not like the radius for a circle or like the side length for a square. So area is one-dimensional, but when you change the radius, as you increase the radius, the area increases at a rate that is not proportionate to the unit. So that's why you just want to be careful.

0:06:09
It's also a good thing to remember that area comparisons are a little bit tougher for our audience, unless – so you kind of want to avoid them for subtle differences, unless you're using it to sort of point out, like, how extreme the difference between the two is. So, area comparisons are just tough for us to make, particularly when the areas are close. So, it's important to just keep that in mind when we're making a visualization. Okay. So, that's it for this video. We learned how to make both a bubble chart really quickly and a unit chart in Tableau. In the next video, we'll continue to learn how to make different chart types.

0:06:49
And remember, I will be uploading this workbook into the Erich Institute's Tableau Public Profile, and a link to that workbook online will be found at the end of the slides in the repository. All right. I hope you enjoyed this video. I enjoyed having you watch this video, and I hope to see you next time. Have a great rest of your day. Bye.