Better Charts

Summary: December sale expected to stay above 60,000 units for the 5th consecutive month. A flattish quarter-on-quarter in the 4th quarter is expected. Analysts forecast a lower sale in 2023.

A recent news report showed a chart on vehicle sales. I reproduced the chart above and thought of improving it. As I am not an analyst in the transportation, I will refrain from making comments and stick only to improving the chart.

At first glance, the chart is cluttered and it was hard to see where the story was getting at. I was also unconvinced with the 3 summary points to the right of the chart, as the graphs do not bring the points out.

The first thing I did was declutter the chart by switching to line graphs instead. I kept the original author's intention to show a month-on-month view. I did not show the data points as it makes the chart untidy. I also reduced the vertical axis granularity. The covered range becomes clearer.

To bring out the points the original author wanted, I added the December 2022 forecast using Excel Forecast formula over the previous 6 months. I also added the a trendline for 2022. Since the original author mentioned a flattish 4th quarter, I switched the trendline from linear to logarithmic.

To make the chart further readable I darken the graph for the year 2022 to draw attention to it, and faded the year 2021 to the background. The chart legend was brought nearer to the end of the graphs on the right.

Let's put the before and the after charts side by side to see the difference

Before	After

With these changes, it is clearer to see the summary point #1 - December sales expected to be above 60,000 for the 5th consecutive month, and point #2 - Expecting a flattish 4th quarter in 2022. I am unable to draw out point #3 - Expecting lower sales in 2023. This insight most likely coming from the industry rather than from the chart.

If the chart was to be presented to those within the industry, I might choose to show the chart as a full timeline instead of overlaying 2021 and 2022. In the chart below, the vehicle sales is seen progressively increasing. A 3-month forecast with confidence level could also be added. But all these is going beyond the original author's intention.

Do you see other further improvements? If you do, go now and improved the chart in your DC-Den!