I’m learning at long last how changing scales can expose patterns. Today I’ve been looking at the Facebook Page of Marks & Spencer (a UK retailer.)

Using a linear scale on the y-axis, we see how engagement has increased rapidly over recent months. That’s pretty much text book stuff for a well-run Page.

But by dropping a log₂(x) scale onto the y-axis (why log 2? I was experimenting after reading When Should I Use Logarithmic Scales in My Charts and Graphs?) we can see a couple of strange patterns emerging.

Notice the distinct vertical lines around October and December 2011, and again in February 2012? Also the horizontal lines that extend from around January to April 2012?

Both can — it turns out — be explained by odd posting behaviour related to photo albums; and could raise some interesting issues of what is and what isn’t best practice.

But the short point is; I wouldn’t have seen it but for the log scale.