Want to Boost Website Profitability? Forget the Averages

Paul Randall  |  March 11, 2016

Paul Randall  |  March 11, 2016


If you look at averages, you won’t find anything particularly interesting.

It’s only when you dig a little deeper that you find real insight.

In World War II, Allied bomber planes were constantly being shot down.

Armor-plating the whole plane would make it too heavy, so extra plating could only be put in the areas where planes were being shot at the most.

A mathematician, named Abraham Wald, was asked to look into this problem.

He began by creating a diagram that outlined the plane and marked where the bullet holes were found on the planes that had returned.


Image source: Fast Code Design

The black areas in the image above are where the plane was shot at the most, so based on that you would say that plating these areas would protect them.

But the thing is, when looking at the averages, people were missing the real weakness.

Wald argued that instead of plating the areas where the planes had been shot, that instead the plane needed reinforcement where the plane didn’t have bullet holes.

What people were forgetting is that the planes returning hadn’t been shot down.

It’s easy to make assumptions with generalized data, but to understand the problem you have to look a little deeper.

Weaknesses can't be found in averages

When looking at analytics, our dashboards are filled with averages: average bounce rate, average time on site, average conversion rate.


The problem is, averages hide variations and anomalies. One event can skew the average and your perception of the information.

By digging into the data you can find areas which aren't performing as well as you would have expected, but these won't jump out at you. They have to be uncovered. Here are some considerations:

  • Look for differences in paid traffic vs organic traffic. Are you paying for traffic that isn't engaging with your content?
  • Identify dropout points for new visitors. Where are you losing potential new customers?
  • Break your conversion rate down by device to identify weaknesses on mobile or tablet.
  • For A/B tests with no significance. Segment your data into mobile and non-mobile to see if trends begin to appear.

It won't tell you how to fix them, or what the problem is; but it will give you an area to focus on for further analysis.

Next time you are looking through analytics, avoid the averages and look for the weaknesses.


What’s your opinion on the usefulness of average web metrics? Do you agree with Paul that the real insights are to be found by looking beyond them? Let us know in the comments below – or join the conversation on Twitter with the hashtag #DecibelSoapbox.

Turn your website into a conversion machine

Paul Randall

Written on March 11, 2016 by:

Paul Randall

Senior UX Architect at Evosite.


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