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I'm trying to create an online survey where the participant hears a series of randomly determined sound files and rates each of them on a likert scale.

We will have around 1000 participants, each hearing 10 randomly determined sounds, with the following condition:

The sound files each depend on two variables and there is one file for each combination:
e.g. If the two variable can take the values [A, B, C] and [1, 2, 3] respectively then there would be 9 possible sound files: A1, A2, A3, B1, B2, B3, C1, C2, C3.

I want each participant to hear an example of each variable exactly once. e.g.
A2, C3, B1 and B2, A1, C3 are both valid series of sounds (no letters or numbers are repeated)
but
C1, C2, A3 and A3, C1, B3 are not valid series (a letter or number has been repeated).

[In my case I have 10 values of each random variable, 100 sound files].

I've tried Qualtrics and REDCap but cannot see how to do this sort of randomization. Is there an online survey creation tool that supports this functionality?
or failing that, can anyone explain how to to this in Qualtics/REDCap?

[I originally asked this question I academia and was advised this was a more appropriate place to ask.]

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  • $\begingroup$ Welcome. Do you have access to MATLAB? Further, although the experiment in itself is CogSci, the question is whether a randomization question is. In the end, the question is about statistical procedures, really. $\endgroup$ – AliceD Nov 27 '17 at 10:59
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    $\begingroup$ I do have access to MATLAB. The plan was to try to use an online service to avoid having to address the hosting/security issues ourselves. The randomisation code itself is trivial to do in MATLAB or python, but we were hoping there would a be way to do it via qualtrics/REDCap etc.. $\endgroup$ – mawir Nov 27 '17 at 11:05
  • $\begingroup$ aha I think I understand. Sort of :) Basically you wish to randomize it online, as in, on the spot when a subject starts a test? $\endgroup$ – AliceD Nov 27 '17 at 11:18
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    $\begingroup$ Yes, we want about 1000 participants, with each participant hearing a different set of sounds. I'll modify the question to reflect this. The plan was to do the randomization when the participant starts the test, but it doesn't seem possible in any of the online survey builders we've tested. We could also pre-generate the random sequences and then send out 1000 different surveys. But this would need to be automated somehow $\endgroup$ – mawir Nov 27 '17 at 11:25
  • $\begingroup$ Only speaking for Qualtrics, but I don't believe there is a way to do this. To get close (randomization within one variable), you could create blocks for each level (A block, B block, etc) and randomly select one within each to be give to the participant. That said, other than hard coding your randomization (as you mention), I don't think this is feasible in Qualtrics. Depending on how far you want to take it, you may be able to write some skip logic on what should be included in the block itself (based on what question was already answered), though I'm not sure this is worth the time. $\endgroup$ – mfloren Jan 8 '18 at 20:12

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