https://www.bloomberg.com/news/articles/2015-12-03/electric-cars-can-t-take-the-cold
This week we had an interesting discussion in class, about when to use heat maps and how to interpret them.
I came across this heat map. The claim is, Since electric cars generate power less efficiently as the temperatures drop, they are sold more on the West coast than other regions of USA. And obviosuly, there are other reasons like West Coast being more technology savvy than the rest, also adds up to the sales.
About the visualization –
- The heat map is U.S electric vehicle sales by region
- On observing we see, that there are 4 patterned boxes for 4 regions and California is in light blue
- On the first glance, one state and other regions seems confusing
- It takes time to interpret the heat map
The Underlying meaning
- The visualization depicts the 4 regions and the sales made in each region in September
- What they have tried to show is, even on the West Coast, California sells the highest number of electric cars.
- The number of cars sold in California, is greater than those combined for Midwest, Notheasrt, South and the remaining West region.
- But, this could be shown through a bar graph as well, comparing sales in California with the rest. That would have been easier to interpret in the first look.
Apart from temperature, factors like population should also be considered. California is the most populated state , as per the region available, so that could be one contributing factor as well.
References –
https://www.bloomberg.com/news/articles/2015-12-03/electric-cars-can-t-take-the-cold