Bounce rate in Power BI differs from GA tremendously

[Anonymous]

Hey everyone, 

I have encountered this problem while using power bi, the bounce rate is clearly different from GA: 

As can be seen above (a screenshot from Power BI) it fluctuates around 40%. For this graph, I used average of bounce rate per date as I couldn't find any other reasonable way to measure the bounce rate correctly. Here you can compare it to data from GA: 

As can be seen, the data are rather constant in GA.

This issue also arises for Pages/ Session and Average Session Duration, basically for every metric that uses Average instead of Sum and is depicted over time. Does anyone know what might cause the problem? 

[Anonymous · Accepted solution]

This is likely an issue with taking a simple average of the Bounce Rate metric.

If you have a page with 1,000 page views and a bounce rate of 20%, and a page with 1 page view and a bounce rate of 80%, Power BI would (depending of course on how your data are structured) reach an average bounce rate of 50%. Google Analytics, on the other hand, would do a weighted average, which in this example amounts to (1000*.2 + 1*.8)/1001 = 20.06%.

For this reason, it is better if you calculate the Bounce Rate metrics yourself. Since Bounce Rate is defined as Bounces/Sessions, you can import these two metrics, then create a measure in your report with the formula

DIVIDE(SUM([Bounces]), SUM([Sessions]))

This should give you the correct result, as Power BI will now summarize Bounces and Sessions across all pages, and then calculate the average Bounce Rate.

[Lucian]

Hi @Anonymous ,

Thank you for this explanation - I was circling around for 1 day and did not find one clear information about this problem. Nither Google Analytics docs did not clearly explain how the Bounce rate is calculated and that the information offered in the Google Analytics Power BI Connector for "Bounce rate" dimention is totally useless.

Your formula gave the exact values in Power BI as the GA Report. 🎉

By any chance, do you know how to get the proper value for the Avg. Time on Page dimension? Because it seems that it has the same problem as the Bounce Rate - the simple average of this dimension does not show the same value as in Google Analytics report.

Kind Regards,

Lucian

[parry2k]

@Anonymous no idea what is your question and what you are looking for. Read this post to get your answer quickly.

https://community.powerbi.com/t5/Community-Blog/How-to-Get-Your-Question-Answered-Quickly/ba-p/38490

[Anonymous]

Thanks for the link @parry2k , I skimmed through.

Let me try again then, my question is basically this: 

Why does the data in Power BI differs from Google Analytic? I know about sampling and all that, but this doesn't seem like a sampling problem as the data are going 'randomly' up and down. In other words, they are not similar to Google Analytics whatsoever. 

Could this be caused by using the average? If so, what could be other way to show Bounce Rate, Pages/Session, Session Duration (y axis) over time (Data as x axis)? 

This is what I mean by using the average: 

The data is taken from GA, it's just Bounce Rate by Date. Looking forward to hearing from you.

[dax]

Hi @Anonymous , 

If possible could you please inform me more detailed information(such as your expected output and your sample data )? Then I will help you more correctly.

Please do mask sensitive data before uploading.

Thanks for your understanding and support.
Best Regards,
Zoe Zhi

If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.