Re-opening study - posibiltities & representative sample

⛑ Community Support
1

Hello,

I put up a study a week back but due to an error (not on the side of Prolific but of the other platform I used to run the survey) I now have uneven distributed people in 8 groups (I split the survey so that questions were slightly different in 8 groups). I aimed to have 144 people per group. I now have have around 120 people in 7 groups and 250 people in one group.

Is it possible to re-open the study in order to get to the desired 144 people per group? Of course I will delete one group, the one for which I have more than I need participants for.

Would it be possible to get new people doing the study? I want to make sure that they are different people.

Also, would this affect the representativeness of the groups? I initally had ticked that I want a representative sample and with support from Prolific I was also able to have other inclusion criteria added.

Thank you in advance!

2

Hello Jaskiran,

In your situation I would consider opening new studies, one for each of the 8 groups (if I got it right, your groups are the treatments or conditions of your study):

  • If study 1 is complete, you can Duplicate it (Action >> Duplicate). This will create a new study with same details, cost info, etc.

  • You can now put on the filter “Custom Blocklist” or either the “Exclude participants from previous studies” filter in order to exclude those Prolific IDs who were part of your study 1. However, please be aware that there have been issues reported by other researchers due to, probably, a current bug affecting these pre-screeners. So maybe it would be wise to give it a try and in case you also experience the issue, wait for a response from Prolific Team.

  • You can select the number of participants for each study on the basis of the gap you need to fill (i.e., 144- number of recruited participants for each treatment)

  • I would proceed by steps, creating each New Study on copy of the previous one, so waiting for each to be Completed before going through the creation and launch of the following one. This, in order to be able to exclude those IDs who take part in all ‘other’ studies, not only your study 1.

Also, would this affect the representativeness of the groups? I initally had ticked that I want a representative sample and with support from Prolific I was also able to have other inclusion criteria added.

I think if you proceed in the way I suggested you should not have problems of representativeness, indeed this is also the way Prolific suggests to proceed in case you want to Increase places to you rep sample study (please see the bottom of this page). Increasing places is indeed an option not available for rep sample studies.

I hope I was clear enough!
Oc tell me if you still have questions or doubts,
Veronica

3

Hi Veronica,

Thank you so much for the detailed reponse! It is very helpful.
I will go for duplicating once I hear back from Prolific too.
Have a great rest of the day!