How does Rayyan estimate time spent on reviews?

The calculation is based on the timestamps of the decisions/labels you put and some heuristics as we explain below.

 

For example, when you click on "Include" at time 0, then another "Exclude" after 2 seconds, the duration between both actions is accumulated to denote that you have been working for 2 seconds. If however, you left the review for more than 10 minutes then do the third action, Rayyan will detect that you have been idle all that time and will increment the number of sessions you have worked on but not the total duration. The fourth action after 5 seconds will accumulate only 5 seconds to the duration.

Rayyan will put an extra minute for each session assuming that you have spent some time looking at the review before making the action.
In this example, the total sessions will be 2 and total duration will be 2 + 5 = 7 seconds + 2 minutes.

The time spent is an estimate only which we think is the most representative of the actual time based on our experiments, but isn't always precise.