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+500 points
~25 mins

Learning Objectives

After completing this unit, you’ll be able to:

  • Explore other chart types.
  • Edit an axis.
  • Use a circle chart to look at trends.
  • Use a line chart to communicate trends over time.

Check: Connect Your Tableau Public Account

If you haven’t already, or if the playground has timed out, log into your Tableau Public account in the Playground window to the right. If you don’t already have a Tableau Public account, sign up for one now, and be sure to activate your account before starting this interactive unit. You can find more detailed instructions in The Tableau Data Model.

Note

The playground resets if your Tableau Public login session expires or if you refresh the page before completing the unit. We recommend completing this unit in one sitting.

Note

Since this is a training data set, we’ve included made-up metrics about viewership and ratings.

Bar charts are a stupendous way to visualize data, but they aren’t the only option by far. Let’s switch to another set of fields and another chart type entirely to look at other trends in viewership and ratings.

  1. Create a new sheet. Tip: Click the New Sheet icon next to the sheet tab Ratings Per Episode.
  2. Double-click My Viewership in the Data pane to add it to the viz. Tip: If you're not sure what table to expand to find a field you want, try using the search bar.
  3. Double-click My Rating in the Data pane to add it to the viz.

Why is there only one dot in the scatter plot?

Well, you’re looking at the average rating by total viewership—across all episodes in all seasons of the show. How can you change this to show us more detail? Add a field to detail!

  1. You need to tell Tableau the level of detail you want in the viz. For this set of fields, Season Episode makes the most sense. Drag Season Episode to Detail on the Marks card. Tip: at the very bottom left of the screen, under the Data Source tab, there’s a status bar that shows the number of marks. It should be 134 marks. If you don't have 134 marks, verify what fields you’re using.

Does SUM make sense to use for viewership?

Yes! Viewership is a cumulative metric. (For example, summing the viewers of each episode of a season gives meaningful information about the total viewership for the season. This is not the case for rating.) You can leave the aggregation alone for the viewership field.

The marks are all bunched up between 6 and 8 for ratings. Does the axis have to include zero to be accurate?

This is a potentially contentious issue, but here we feel OK saying no. Bar charts should always start at zero, but for line charts and scatter plots, sometimes starting at zero masks the differences that we care about. People don’t tend to use the full 0–10 rating scale, and a difference of 7.9 versus 8.5 is meaningful.

Starting at zero makes the relevant interval hard to see. However, always use caution when changing the scale or starting point of an axis. See Guidelines to Recognize Misleading Charts for more information.

  1. Right-click on the My Rating axis.
  2. Then, select Edit Axis…
  3. Uncheck the box for Include zero.
  4. Click the X to close the dialog.

The marks now spread to fill more of the chart.

Question for Analysis: Does the Network Impact Viewership and Ratings?

To explore this question, you use filled circles to represent network impact.

  1. Drag Network from the data pane to Color on the Marks card. Tip: If you’re not sure what table to expand to find a field you want, try using the search bar.

The marks are now colored according to the Network. You can do some quick formatting to make the marks more easily distinguished.

  1. Click Shape on the Marks card.
  2. Then click the filled circle.
  3. Click away to close the control.
  4. Click Color on the Marks card and set the opacity to 80%. This makes it easier to see when marks are stacked on each other.
  5. Click Size on the Marks card and set the size at 35%, or whatever looks good to you.

It looks like there are distinct clusters for each network. BBC Two, in orange, has lower viewership but high ratings. BBC One, in blue, has high viewership and high ratings. And Channel 4, in red, has middling viewership with some high ratings but it also has the lowest rated episodes.

  1. Double-click the words Sheet 4 at the bottom and rename the sheet Network Trends.

Question for Analysis: How Does This Relate to When the Show Was on Each Network?

Let’s try to suss out the analysis using a line chart.

  1. Create a new sheet.
  2. Drag Airdate to Columns.
  3. Drag My Viewership to Rows.
  4. Drag Network to Color.

What does the viz tell you?

(Remember, this is made-up data for training purposes.)

The show started on BBC Two, and the viewership grew each year. In 2014 the network switched to BBC One and viewership continued to grow. In 2017 the network again switched, this time to Channel 4, and the viewership dropped. Channel 4 struggled a bit with viewership, with a bump in 2020 and the lowest viewership in 2022. However, the latest season in 2023 picked back up and is comparable to 2014’s viewership.

  1. Name this sheet Viewership Over Time. Make sure you're on this sheet when you check the challenge.

Sum It Up

Congratulations. Throughout this unit, you explored key concepts in data analysis—how it’s a flexible cycle rather than a wizard-like series of steps, how finding the right visuals and minding the details help you communicate the right data. But perhaps most importantly, you need to be curious and keep asking questions, check your assumptions as you go along, and not be afraid to make mistakes.

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