How is median completion time calculated?

I ran a small pilot study with 5 people. You can see their completion times, and the “median completion time” at the top.

The median of those numbers is definitely not 8. Where did the 00:08:00 number come from?

Oh, I see that I entered 8 as the estimated completion time when I created the task. But it doesn’t make sense to me that this would result in showing that as the median time.

Prolific displays the researcher’s estimate of the completion time as the “median completion time” until some threshold of responses is reached (I’m not exactly sure what that threshold is, but I think it might be N >= 10). I’d guess the purpose of this is to avoid participants seeing an extremely noisy estimate of median completion time when the study first opens.

Thanks Matt

I never knew. I was wondering why my estimate was being shown as “Median Time” but now I see that with enough participants (I think 10 may be right) that it has changed to the real median time.

This is a bit of a shame in a way because I often create a preliminary study with ten participants and the Median time shows only my estimate, so I can’t use it as a basis for the time to stipulate for the subsequent main study.