Millisecond Forums

How to randomize subjects in Inquisit web with an alphanumeric subject ID

https://forums.millisecond.com/Topic19734.aspx

By James Gren - 9/21/2016

I'm planning to pass my participants from Qualtrics through to Inquisit Web 4, which I've previously done successfully, passing Qualtrics ResponseID through the URL.

So far, so good.

However, I've now run into a problem because in my next study I have 3 inquisit scripts that I want to run in different orders. Previously I've used the "/ subjects = (1 of 6)" format, but this doesn't work on the alphanumeric participant ResponseID code that Qualtrics generates. I can't work out how to assign a numeric code in Qualtrics, so any suggestions on how to get this randomization working would be helpful. The first two batch elements of my web file are below.

<batch>
/ file = "AMP_EXPL v4_48.iqx"
/ file = "AMP_IMPL v4_48.iqx"
/ file = "global.iqx"
/ file = "demographic.iqx"
/ subjects = (1 of 6)
</batch>

<batch>
/ file = "AMP_IMPL v4_48.iqx"
/ file = "AMP_EXPL v4_48.iqx"
/ file = "global.iqx"
/ file = "demographic.iqx"
/ subjects = (2 of 6)
</batch>
By Dave - 9/21/2016

The solution is to switch the /groupassignment method to something else.

<batch>
/ file = "AMP_EXPL v4_48.iqx"
/ file = "AMP_IMPL v4_48.iqx"
/ file = "global.iqx"
/ file = "demographic.iqx"
/ subjects = (1 of 6)
/ groupassignment = groupnumber
</batch>

<batch>
/ file = "AMP_IMPL v4_48.iqx"
/ file = "AMP_EXPL v4_48.iqx"
/ file = "global.iqx"
/ file = "demographic.iqx"
/ subjects = (2 of 6)
/ groupassignment = groupnumber
</batch>

Have the launch page provide a random or sequential group id (via the web experiment's settings).
Cf. https://www.millisecond.com/forums/Topic13856.aspx

If you don't want to or can't use the group id for assignment for some reason, you can also set

/ groupassignment = random
By James Gren - 9/21/2016

Brilliant! I'd been trying variations on that, but I think I'd tried "group" rather than "groupnumber".

In a related downstream problem, my IAT is also reliant on a group allocation, can I check that using the same addition of "/groupassignment = groupnumber" would also be an appropriate solution.

<variables>
/groupassignment = groupnumber
/ group = (1 of 4) (block1=CHpractice;
block2=PNpractice;block3=CHPNtestinstructions;block4=CHPNtest;block5=NPpractice;block6=CHNPtestinstructions;block7=CHNPtest)


(I'm aware that the variables block is depracated)
By Dave - 9/21/2016

Yes, /groupassignment works identically in <batch>, <expt> and <variables>, i.e. you can use it in the same way.