🤔 Ask Anything Thread (Newbie Friendly)

Hello, I launched a study on May 23rd for 10 participants at 2:30pm EST. I included a demographic screener for participants in the USA. I didn’t get any active users until 5:00 AM EST on May 24th; all ten participants submitted between 5 and 6:00 AM. I’m a bit concerned because I expect it is very unlikely that no one who lives in the US saw my study until 5AM on May 24th. Is it possibel for a single user to “game” prolific and do my study ten times using ten different prolific IDs?

Dear Psas
Welcome to the forum :slightly_smiling_face:

There was a Prolific glitch yesterday that meant that recruitment was intermittent. Jon, the forum leader, informs us that it is fixed now

So the weird intermittent recruitment that you experienced is likely to have been fixed, and I think that it is unlikely that what you were experiencing was due to participant maleficence.

I hope that does some way to easing your concern,


When is payment converted from dollars (what I enter) to pounds? I’m in the USA and all of my participants are in the USA. A participant says they are short about $7. If I use the exchange rate from a few months ago when I launched the study, then the amount is pretty much on the money.

2 posts were split to a new topic: Is it possible to see survey participant’s income?

Hi @David_Martinez , that’s a great question and I don’t know the answer.
@Jon & @Community_Leaders does anyone know if the exchange is processed at the time of researcher → participant account or at the time of participant account → withdrawal?

A post was split to a new topic: Prescreening and surveying individuals with cardiovascular disease

Dear David and Paul,

I am sorry I don’t know the time of exchange either.

I think this calls for a kind response from our leader, @Jon


1 Like

Hi! We have run studies through Prolific before, but not one where we need participants to write proper e-mails. Do you have experience with how to ensure that participants seriously participate in such a writing task? We would like to avoid responses from unmotivated participants.

We were thinking of giving bonus payment based on the completeness and complexity of the written e-mails, but some people may just not write very eloquently. Another concern for this type of task is what time estimation to use. Some people may gladly take an hour to write three great e-mails, whereas others can provide the same quality in 20 minutes. It would be great if you have any thoughts on this.

1 Like

Hey @David_Martinez ,

This one took a bit to get my head around - you actually get the exchange rate in place at the time you request a quote for your study, not when you launch. In other words, if you get a quote for a study on 1 May, but don’t launch the study until 25 May, you’d have the 1 May exchange rate in play when you pay out participants. This would suggest to me your calculation of the earlier exchange rate is more close to correct.

The $7 shortfall could come from when the participant cashes out their payment. Payments to participants are credited into their accounts in GBP (£) rather than USD ($) at the study’s exchange rate. Cashouts, however, do not inherit the exchange rate from study itself, so a participant would cash out at the current day’s exchange rate, rather than the study’s exchange rate.

Continuing the analogy from above, if you quoted for your study on 1 May, launched on 25 May, and paid out your participants on 27 May, the participants would receive their payment in GBP at the exchange rate calculated on 1 May.
If the participant then decided to cash out their account from GBP into USD tomorrow (28 May), this would use the exchange rate on 28 May–not the exchange rate on the date of payout or the date the study was quoted. There’s a bit of flexibility here for participants, as they can choose to cash out sooner, or wait until the exchange rate is more favourable to the currency in which they’d like to be paid out in.

My guess is that this is where the shortfall comes from. If you’d like more specificity, our great Support team can look into this for you: to do so you’d need to raise a support request and provide them with the participant ID and the study ID.

Hope that helps - I’ve learned a lot myself in finding this one out! :laughing:

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!

1 Like

4 posts were split to a new topic: Decreasing amount of no-shows for interview studies

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,


2 posts were split to a new topic: How to generate a supplier form for Prolific?

3 posts were split to a new topic: Exclude participants from previous studies

A post was merged into an existing topic: Exclude participants from previous studies

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.