Our Metrics intern, Eric Hergenrader, did some terrific work analyzing fluctuations in Firefox usage. Using a linear regression, he found that this summer’s decline in Firefox use was largely in line with expectations; a 2-3% decline in July and August is typical. In addition to seasonality, Eric found that three factors driving usage drops are weekends (-18%), holidays (-30%), and Firefox releases (-13.5%).
Two months later, Eric’s model does a remarkable job predicting future usage. Below, I have plotted actual against predicted usage. The correlation between these two lines is remarkable. Since September, the average prediction was off by just 1.63%!
To better understand daily growth variations, I created a heat map that visualizes month over month usage growth. Each cell contains one day’s growth rate over the same day of the week, 28 days earlier.
- Strongest growth occurs during Spring and Fall
- Periods of growth and decline are clustered
- Growth is outperforming predictions by 2.58%
We must be careful not to overreach with our conclusions. We are working with a limited range of data and have likely missed significant confounding variables. That said–thanks to Eric’s work–we’re off to a great start. Please leave your thoughts and any suggestions on how to improve our projections in the comments.