Calculated Scores

Presenting Calculated Scores in MediaLab

Now that we have calculated a number of variables from the current session, we can present these values back to the subject. Take a look at item #15 in the self-esteem questionnaire:

You have <rselabel> self esteem <face>

You scored <rse> out of a possible 6.

Your average response time was <rsert>ms (<rsertspeed>).

We are presenting six calculated variables here—all from the responses.xls file. On the second line of the above question wording we see where we are using the calculated self-esteem score. We do this by placing the name of the calculated variable in angular brackets like this: <rse>. That's all there is to it—using this method, you can insert the value any calculated variable into the question wording of any MediaLab item.

Following the same idea, we calculated and presented whether the subject was high or low in self-esteem by using the calculation for <rselabel> as follows:

=IF(B29>3,"high","low")

Using Excel's language for conditional logic, here we're saying that if the subject's calculated self-esteem is greater than 3, then they're "high" and that otherwise, they're "low". Calculating and presenting the subject's average response time, whether it is considered "slow" or "fast" are additional examples of the same idea—calculating new variables from gathered data and using those values in the same session.

Save Calculated Variables to Your Data Files

You can save calculated values along with your other MediaLab data. Create simple placeholder variables in your questionnaire by using the Custom item type with no filename. When such an item is encountered, MediaLab will check to see if the variable name exists in your responses.xls file. If it does, then MediaLab will record the value for that variable in your regular data files. In other words, by using the same variable name for the placeholder and calculated variables, MediaLab will know which values to grab from responses.xls and store in your regular data files. Note that MediaLab will be grabbing the current value of the calculated variable if and whenever it comes across the placeholder item during the session--i.e., location of the placeholder within your session could be an important factor.