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Thread: Can DirectRT Perform Needed Randomization?

  1. #1
    Join Date
    Aug 2007
    Posts
    13

    Can DirectRT Perform Needed Randomization?

    The attached csv shows a draft of a paired comparison study we want to conduct. Each of several pairs (probably all possible pairs) of stimuli will be experienced by a subject; after experiencing each pair of stimuli the subject will be shown one word at a time from two lists of words, and will be asked which stimulus is most like the word.

    I need to randomize the left-right presentation of the pairs of stimuli, probably across subjects, and perhaps (if we find there is enough time) within subjects (on repeated presentation of the same stimulus pair). Can DirectRT do this, and if so, how? We don't want to have several input files, one for each set of possible left-right presentations.

    Also, for this study, we may need to have an administrator physically presenting the pairs of stimuli to each subject. We want to randomize the pairs (after an initial practice block of trials), and we can certainly do this using the BGR field. But in practice the administrator may need to know the series of pairs of stimuli (and their left-right presentation) just before the subject starts the experiment. Is there a way to have DirectRT randomize these pairs of stimuli, and to inform the administrator what that random order will be?
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    Last edited by jarvis24; 09-27-2007 at 03:47 PM.

  2. #2
    Join Date
    Nov 2005
    Posts
    3,328
    Sorry, I'm unclear about what you are trying to do. Can you elaborate, by the way of a concrete example, on how a few trials might look to a subject (i.e., using specific stimuli). That might help me better follow your csv template.

    In the mean time make sure you check out this sample that talks about dealing with the yoking of random pairs just in case it's related to what you're tryiong to do:

    www.empirisoft.com/directrt/help/directrt_samples_v2006_yoking.htm

  3. #3
    Join Date
    Aug 2007
    Posts
    13

    About randomizing left-right presentation and knowing the randomized order of pairs

    Attached is the paired comparison experiment I sent earlier, this time with the various .txt files called by the input file. If we continue to utilize a paired comparison protocol then I would like to have DirectRT determine randomly which of the two products in each pair will be placed on the Ss left and which on the right. Also, I would like to have DirectRT determine the order of the various pairs of stimuli, but because an administrator will actually have to give these stimuli to each S as the trial continues I would like to have the administrator know the order of the randomized pairs in advance of each S's trials. Is this possible with DirectRT?
    Attached Files Attached Files

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