Complex Skips

Just as calculated variables can be used as information we can present back to subjects, they can also be used to help us with skip logic. For any experiment variable you have entered in the reponses.xls file, you can specify or calculate a variable to skip to when that item is completed. If the current MediaLab item is listed in the variable column of the responses.xls file, then MediaLab will check the skipto column when the item is finished to see where it should go next. If there is no skipto value then no skip will occur.

Let's take the fill-in-the-blank age question for example. Currently, there is no skipto value. What would happen if we typed "debrief" into the skipto column for that item? When the age item came up in the MediaLab session, MediaLab would see that age is listed in the responses.xls file. It would see the skipto value of debrief and send the subject to the last item in the questionnaire because it is named debrief. If you have used MediaLab's skipto function in the past, this is pretty standard stuff.

Where it gets interesting is in the fact that you can now use the responses.xls file to calculate skipto values. Instead of placing a static value in the skipto column, we can compute a variable based on what's been happening in the experiment. Let's say that we want to use the subject's self-esteem score to determine what happens next. If they scored extremely high, we want to administer a scale which measures socially desirable responding. If they scored extremely low then we want to administer a depression inventory. If they scored in the normal range, we'll skip them to the end of the session.

Take a look at how we do this by checking out the formula in C26, that is the skipto value of the essay item, ess1:

=IF(B29<2,"dep",IF(B29>4,"sdes","debrief"))

In this formula, you can see three items from the questionnaire file—dep, sdes, and debrief. These are our three skipto candidates. The conditional logic of Excel is applied to say: "If self-esteem is < 2 then dep otherwise if self-esteem is > 4 then sdes, otherwise debrief."