Distribution
Within monitoring, a distribution is meant to show users a quick overview of how experiences are divided. This is helpful as the 75th percentile is only expressed in a single number.
Pagespeed data can be overwhelming. That's why -depending on your settings- our dashboards try to limit the amount of data. You can enable our advanced mode in your profile settings for free though.
The question that a distribution aims to answer
A distribution is able to answer other questions that go beyond the 75th percentile. For example:
- While your 75th percentile number could be bad, you might still want to know how many more pageviews resulted in a good experience.
- When you get a green score for the 75th percentile, you might still want to know how many more pageviews resulted in a good experience.
That's what a distribution is answering. In the case of Core Web Vitals, it is showing percentages of good, moderate and poor experiences.
Distributions in PageSpeed Insights
This can also be seen in a PageSpeed Insights report:
Over here, we can see that the 75th percentile FCP score is stuck at 2.1 second. This means it isn't within the 1.8 second threshold and thus not passing this metric. By looking at the distribution, we can see that this site is 10 percentage points away from passing this metric, as it's still 65% of pageviews that is resulting in a good experience.
When you're into pagespeed optimization and want to see more fine-grained distributions, you might want to consult a histogram chart, if available. RUMvision offers histograms in the technical tab.