How To Analyze Max Differential Scale Data
In FluidSurveys, MaxDiff is referred to as a Max Differential Scale. It is setup in Q as follows:
- On the Variables and Questions tab, change the Variable Type of the data from Text to Numeric.
- Press . This will cause the numeric variables to all be grouped together (provided that you have not clicked anything else along the way).
- Right-click on the select variables and select Find/Replace > Formulas and set Find what to Q.AsNumeric and press Replace all.
- Reorder the variables whose labels indicate they are in Set 1 appear first, followed by the variables in Set 2, etc. While doing this, ensure that the order of the alternatives within each set remains unchanged.
- Modify the Labels so only the names of the alternatives are shown. That is, remove the | Set 1 - Numeric information. The easiest way to do this is by right-clicking and selecting Find/Replace > Variable Labels and Find what (without the quotation marks) to " | Set*" and press Replace All.
- Right-click and select Set Question and change the Question Type to Ranking.
This process is highly sensitive to errors. Each of these steps needs to be performed without any error of any kind. Refer to MaxDiff Specifications for more detailed information about the setup of MaxDiff data.
If you get a message that (The question in the blue or brown drop-down has no data. Please check: the question(s)' Values in the Variables and Questions tab, and any weights or filters.), this means that either:
- There is insufficient data to compute utilities.
- An error has been made in the setup process.