How is median completion time calculated?

1

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

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

2

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.

3

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.

4

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.

Tim