🤔 Ask Anything Thread (Newbie Friendly)

If I want to change a detail of my study, I have to end and then duplicate the study I want to change. Will participants who completed the original one be able to sign up for the duplicated version that has a change? I do not want that.


Dear MIE

Welcome to the forum :slightly_smiling_face:

No, you are in luck (? I mean Prolific has thought of this) a custom blacklist will be automatically created to prevent those who have taken the study from taking it again.


Awesome. Thanks Tim!

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I ran a study with 150 places. It completed.
I wanted to add 250 more and make the study active again.
I tried to add 250 places (for a total of 150+250=400), but was quoted for the full 400, even though I already paid for 150 of them.
So, I figured I misunderstood and I put in 250 as the total, but I was charged for the full 250, even though I already paid for 150 of them. This study is currently active.

How can I run the remaining 150 (=400-250) participants in this study? I already paid for them, but I won’t be able to access those funds, because when I try to add places to the study, it says I owe more.

Am I misunderstanding how this works?

Thank you in advance.

Dear Al

Welcome to the forum :slightly_smiling_face:

I am sorry I am finding it difficult to understand.

You write that you have run the study for 150

I ran a study with 150 places. It completed.

And then a further 250 participants for a total of 400.

Then you ask

How can I run the remaining 150 (=400-250) participants in this study?

Which, forgive me for my misunderstanding, seems to contradict your earlier statement that you had already run the study for the first 150 which completed, So I am not sure why you want to add another 150 participants to the study.

I think you will be charged for only the participants that have completed the study, though when you add participants you will be given a quote for the complete study including the earlier (150) participants and this has confused people in the past. Is this the issue?

I am sorry for my lack of understanding. I look forward to you clarification.


Dear Al

I am sorry, I get it now.

When you add participants to a study, both the number of participants and cost displayed is cumulative.

So after you initial study 150 participant study completed, and you added participants to a cumulative total of 250 you will only have added and been charged for 100 more participants.

You can now increase the places to 400 which is the cumulative total, and the charge displayed will also be for the cumulative amount (150+100+150). The funds to do this should be left in your account.

Prolific needs, imho, to stress that the amounts of participants and costs are cumulative when places are added to an existing study.

I am sorry for not paying more attention to your earlier post.

I hope this clears things up,


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I have run an experiment written with JsPsych hosted on my university server, and a large amount of successful submissions (with completion code) does not have any data or record on my server database. However from the participants’ ends it seemed to have worked just fine. I have not pre-screened on Prolific (a huge mistake on my part) but have piloted the study directly using the link to experiment instead.
I would of course like to pay participants for their work and time but it would mean a large amount of money in for no data.
I wonder if this has happened before and if there might still be a chance to know whether these data are retrievable. Thank you very much! This is my first time asking questions on the server, please let me know if anything is amiss.

Dear Suya

Welcome to the forum :love_you_gesture:

I am afraid that this would appear to be a problem with your university server survey application and or database.

The only time I can remember this happening before was with a Qualtrics based survey were it was necessary to download an excel file before the data was visible, for reasons unclear to me.

As I wrote at that time, are the times to completion shown on the study results page consistent with the participants having completed the survey? If so, and especially since the participants are saying they completed the survey without issue, there is a chance that the data will be in your university server somewhere.

However, Googling ‘Jspsych data disappeared’, I find that others have had a similar issue that does not seem to have been happily resolved, where the final post on the thread presents one possible reason for the lack of data

I.e. the participants were given the Prolific completion code at the end of the JsPsych survey before the submit (or similar) button, and did not click submit.

I hope that this is not the reason in your case.

If unfortunately this was the reason, you might try email your participants to ask them to complete the survey again, some of your participants may be so kind as to do the study again, since they know what they will be asked, perhaps for a lesser payment in the form of a bonus. I am not sure how this sits with Prolific policy.

I am sorry I can’t be of more help.


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Thank you for the welcome Tim!

Knowing it’s not a prolific issue, I will dig further for solutions in those directions you pointed at, so this is definitely very helpful. Thank you very much for your speedy reply!


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Hi there!

I am setting a study and I see Prolific has the function of recruiting balanced sample in terms of gender. However, as I also use other sources to collect data, I hope to over recruit males on Prolific if possible, i.e., I would hope to recruit 70% males and 30% females instead of 50-50%.

Is there a way to set is up in Prolific?

Many thanks in advance,

Dear Peiyao

Welcome to the forum :fireworks:

I am afraid that, as far as I know, the only gender balancing is for a 50/50 split of males and females. Do you think I should submit a feature request for a different gender “balancing”?

In order to have a different split you need to set up two studies, and set one to male and the other to female and set the number of participants to meet your requirements.

Setting up a study is quick since you can use the “Duplicate Study” function from the menu top right.

I am sorry I don’t have better news,


Dear Tim,

Many thanks for you quick reply! Setting up two studies does sound like a great alternative option. I think adding a customisable gender balancing feature would be very useful, if that’s feasible to achieve!

Best wishes,

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