Benford’s Law Analysis and Sparklines
[Benford’s Law Analysis with Sparklines](//vpj.github.io/images/posts/benford-sparkline.png)
The image shows first-two-digit distribution compared with the expected values based on Benford’s Law. What is new here are the sparklines on the right most column which shows the timeline of number of transactions for each first-two-digit combination. For first-two-digits 46, 47, 48, and 49 you don’t see a large variation from Benford’s law, but you see spikes in the sparklines that moved from 49 to 48 to 47 to 46 with time - something to be investigated!.
Sparklines are “data-intense, design-simple, word-sized graphics” according to its inventor Edward Tufte. Before we had sparklines, we used to filter by first-two-digit combinations that deviated significantly from expected value to figure out if there’s something actually wrong. Intuitively, the first thing we examined in the filtered data was the timeline - it’s usually normal if there is no change overtime, and problematic if there is a bump. We haven’t tried out Benford’s Law analysis with sparklines much, but we believe it will be quite useful; what do you think?