Predicting Monthly Car Sales: The Residuals are the Story

I’ll produce predictions for US car sales by manufacture every month. There are already several blogs that describe the industry and sales that do a great job. Autoblog by the Numbers and Counting Cars are some to mention. 

Unlike their analysis, I’ll try to focus on the residuals (the stuff I can’t predict) to tell the story. To highlight the difference, I think its instructive to look at what Autoblog mentioned.

The Autoblog article (link above) highlights Mitsubishi for increasing sales. However, my prediction for Mitsubishi sales are pretty much exactly what the sales were. In essence, given this model, we didn’t learn much. On the other hand, Land Rover and Jaguar had the largest residuals (in percent terms) and Land Rover and Acura had the largest deviance (Residual / Variance). I think these results are more telling because we didn’t predict them correctly; something might have changed. 

I’ll publish this on a new blog: datAutomotive.

Here is a  Shiny App For Car Sales and below are graphs / tables of my current analysis and future predictions.