compare=true, and compare_start to choose where the compared period starts.
How it works
Turn on Compare in the period bar. The previous period is the same length as the selected one, immediately before it:
You can also choose where the compared period starts. It always has the same length as the selected one:
A compared period that ends after the selected one starts is not accepted, because the two would overlap.
Two things change on screen:
- Charts draw the previous period as a dashed line over the current one, aligned by position in time.
- Numbers show the change, such as “+12%” for requests or a lower response time, next to the value.
Reading the change
- More requests is not automatically good or bad: it depends on whether you launched something or a bot arrived.
- Response time and error rate going up is the part to act on. Check Errors and Performance.
- A very small base exaggerates percentages: from 2 errors to 4 is “+100%”. Look at the counts too.