Access to more studies than expected

[MarjolaineC]

Hi guys,
I am having trouble with some of my participants. They are apparently able to access studies for which I did not send them links.
My studies are launched on FF directly, with an access code, and I send the link to my participants. They are divided into three groups and should participate in a definite number of studies. 
A participant wrote this morning saying that each time he clicks a link he has access to the three types of studies. How is that possible? How can I fix it? More surprising, this is not the case for everyone, most of my participants only have access to the studies they should. 
Many thanks!
Marjolaine 

[Rachel - Participant Affairs]

Hi MarjolaineC, 
Thanks for your message! Are participants simply able to see all of the studies you have posted or are they actually able to participate in studies that they are ineligible for? If the latter, are there different access codes for each session? 

The first thing I would check is the eligibility criteria you used to set up each session (this tutorial on running multi-part studies may be helpful).
Best,
Rachel

[MarjolaineC]

Hi Rachel,

Thanks for the answer, I am going to check the tutorial.
They are actually able to participate in studies.
The access code is the same for all sessions (parents and children are participating in a training study, they need to connect three times a week for 8 weeks, and some parents have two kids in the household taking part in different training groups, having different access code is not really possible, as it will add too many details to pay attention to). And as parents need to be able to connect on two different study types for their two kids, I cannot either restrict the access to the study...
I ask these participants to connect only on the training sessions they should and disregard the other, even if they have access to them.

Best,
Marjolaine

[Rachel - Participant Affairs]

Hi Marjolaine,
Concurrent sessions from different studies with the same access codes will be accessible to anyone with the access code. Without the use of prerequisites or different access codes, it's not possible to restrict access to the studies you wish to prevent participants from participating in. 

Since you have a multi-day study, you could set up the prerequisites so that, in order to participate in Day 2, participants must first complete Day 1, to participate in Day 3, participants must first complete Day 1 and Day 2, and so on. This would ensure that participants completed studies in the desired order. You could also use prerequisites to prevent participation in studies from Group B, once a participant has completed a study from Group A, but since you have parents with children in more than one group, that sounds like it might not be desirable.

Hope that helps!
Rachel