Multiple y-axis and combo charts

1. Multiple y-axis and combo charts

Now that we've reviewed setting up simple x and y axis charts, let's talk about a more complicated scenario.

2. Compare multiple data columns

Sometimes we need a chart to compare two or more columns, such as comparing revenue to profit, or in Oakmark's example, comparing a count of customers served to a count of calls received. Maybe we want to know - as calls increase, does the number of customers also increase proportionately?

3. Compare multiple data columns

To compare them on a single chart, they must first share an x-axis. So, if we're talking about calls received and customers served

4. Compare multiple data columns

they must share a column like [Call Date] as their x-axis.

5. Y-axis needed for interpretation

Assuming the x-axis is shared, we must also have a y-axis that helps interpret both columns; but what if our data points, such as revenue and profit, have wildly different scales? Or what if the data points have different units altogether, as in the case of comparing calls to customers?

6. Format y-axis accordingly

To choose the best chart type for comparing 2 or more data columns, we must understand both the units and scale of the columns and choose our y-axis formatting accordingly. When the two data columns share the same units, such as a count of calls received and a count of calls escalated (both having calls as their unit) it is acceptable to have them share a single y-axis.

7. Different scales need separate y-axes

However, if they exist at wildly different scales, perhaps escalated calls represent a tiny fraction of overall calls received, it's usually best to move one of the data points to a second axis and use differing colors and label formats, to more easily see how one data point relates to the other.

8. Different units require two y-axes

In cases where the data columns have differing units, such as in comparing a count of calls to a count of customers, then it is always advisable to move one data column to a second y-axis. Otherwise end users may misinterpret the values being shown to them.

9. Combo charts

We've focused on line and area charts so far in this course, but most chart types in Sigma with a y-axis can have either multiple fields sharing a single y-axis, or a second y-axis. Coming up, we'll learn about a new type of chart - the combo chart. It's commonly used when displaying multiple data columns on a single chart because it can accommodate a mix of line, bar, area or points on the same chart.

10. Combo charts

Combo charts are best suited for time-based charts, and the combination of, say, bars and lines on a single chart, should be carefully considered to enhance user insight and experience and not clutter the chart.

11. Combo charts

In general, it's important to remember that not all data is suitable for a shared y-axis display or for a combo chart. Sigma developers should carefully consider the use case and intended audience when selecting chart options. This is particularly true when using a shared axis chart, which can be unfamiliar to some end users.

12. Let's practice!

In the next video, we'll see how combo charts work as we help Oakmark Bank set up some charts comparing multiple data columns.

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