Millisecond Forums

group assignment with web scripts

By mrsuther - 10/31/2016

A web script that I posted doesn't seem to be performing the group assignments as expected.
I have 108 different groups to assign to 324 potential participants.
I selected the option that assigns groups sequentially, and when doing this I assumed that participant 109 would be assigned to group 1, and that the group assignments would continue as such.
However, in my output I see that participants were assigned to groups that don't exist (i.e. group 109).
Thus it is unclear which group these participants were assigned to.
Is there something I'm missing, or has anyone else experienced something similar?
Thanks in advance! :-)
By Dave - 10/31/2016

A (in your case sequential) group number is generated when a participant visits the launch page -- this happens regardless of whether said participant ultimately decides to actually start the experiment or just leaves the page.

Condition assignment works on the basis of the provided groupnumber *modulo* the number of conditions. So, with 108 conditions and a groupnumber of 109, that participant would have received the 1st condition, because

109 modulo 108 = 1

just like

1 modulo 108 = 1

I.e., you can determine the condition that was administered based on the given groupnumber. More about that here:

Hope this helps.