Equally distribute participants into 2 different lists in OSWeb Experiment
Hello everyone!
I would like help on assigning participants to one of the two possible lists based on their subject number in an OSWeb experiment. Basically, I want to equally divide 24 participants between lists A (odd numbers) and B (even numbers).
On the JATOS documentation site, they offer a solution using Batch Session Data. They also have an "Randomize Tasks Between Workers" template for this. I downloaded the template, but I'm not sure how to adapt the code to my experiment. For example, I don't need the "continue" button or for the participants to know which list they are assigned to. The template I mentioned is found here: https://www.jatos.org/Example-Studies.html
Another option I found here is to simply create 2 different loops and change the "run if" conditions depending on subject parity in OpenSesame. I'm also not sure if this will work because I can't find exactly how JATOS assign subject numbers to participants (e.g. do general worker IDs begin from 1,2, and so on; does an abandoned session still get saved as a participant).
On a related note, when you use the OSWeb function in OpenSesame, the "possible subject numbers" field is set to 0,1 by default for me. What does this imply? Sorry if this is a very obvious question, but I just wanted to make sure what it means before tinkering with it.
Thank you for your time and patience! I appreciate any help I can get.
Comments
Hi there
I've been working with online experiments for a bit now and I think that you are right, in that worker ID's are assigned to any participants (even those who do not finish it). You could always include a bit of javascript in the beginning that uses the Math.random() function, then round that, and assign participants to a list based on that result being 0 or 1. That should result in about a 50/50 spread (but you can't guarantee that).
If you need absolute guarantee, you could work around it by simply uploading the experiment twice, once with list A and once with list B, and send out the links accordingly. But these are just work-around solutions, I'm sure there are more advanced users who know how to implement this more neatly.
Best
Jelle
Hi Jelle!
In the end I would prefer a guaranteed balance, so I think your second suggestion works for me. As our administrator suggested, I could upload the 2 lists as different experiments on SONA systems and make participating in one a disqualifier for the other and vice versa.
Thank you so much for your reply!
Kind regards,
Patricia