Hidden analytics traps: percent change

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Quick, take a look at this performance chart of percent change in your analytics:


Now tell me, is the person responsible for this getting fired?

Obviously, based on the title of this post, you might be a little more cautious about how you answer that question – but the average manager, director, VP, or C-suite executive might not be.

Okay, second performance chart for you to take a look at:


So, what do you think? Is the person in charge of revenue here getting fired or promoted?

If you’re a rational business leader, the up-and-to-the-right nature of this graph obviously says that the person in charge of it is doing a good job.



This is the hidden danger of percentage change calculations. They’re useful for understanding how much something has grown, but they can be skewed significantly if you’re talking about big jumps relative to the size of the data. The difference between 1,000 and 1,001 is the same in absolute terms as the difference between 0 and 1, but the latter is an infinitely bigger jump.

This is why you need to look at absolute data whenever you’re looking at percentage change data. It doesn’t matter whether you’re talking about Twitter followers, lead generation, ROI, or company revenue – make this a standard rule to practice. If a vendor, supplier, subordinate, or peer comes to you with only percentage change data, ask them with vigor and confidence to also see the underlying data, otherwise you may be getting only part of the story (and likely the part of the story that makes them look good).

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