I am making an official request to Google Analytics – please add the option of displaying medians for site data. For some reason in the analytics industry, there’s been this adoption of means (averages) as a measure for certain site behaviour. Average page views per visit, average time spent on site, average everything. But anyone with even rudimentary knowledge of statistics knows that averages aren’t necessarily great representations of performance because they don’t provide any indication of variability.

Consider the following hypothetical site dataset for 10 visitors:

I won’t include the calculations, but if you perform them correctly, you get the following results:

Average Time on Site – 86 seconds or 1.44 minutes

Median Time on Site – 15 seconds

Okay – so the first criticism is that this is a hypothetical scenario with numbers that I created. True, but it’s not unusual (from my experience) to find that 75-80% of visitors leave within 30 seconds after arriving at a site. Someone might draw a conclusion that a site is performing well if they were to see the average time on site being 1.44 minutes. If I were an advertiser on that site…………….yeesh.

The second point is about functionality. I can (sort of) assess whether averages are being skewed by looking deeper into data. For instance, I can go in to Google Analytics and see what percentage of visitors are leaving within a given time range (e.g. 60% of visitors are leaving within 0-10 seconds). This is somewhat helpful, but given that GA is already calculating averages it can’t be much of stretch to include a calculation for medians either (it’s a simple function in Excel after all).

If I had immediate access to the data above (86 seconds versus 15 seconds), I would know that there is a lot of variability within the data and that a small percentage of visitors are accounting for a large percentage of time on site.

By the way – did anyone like the (nerdy) play on words in the title?

Clay