This article provides an in-depth explanation of AskiaDesign‘s built-in capacity to manage MaxDiff data collection & analysis methodologies. For those of you who, like me, need a short reminder of what MaxDiff is; this is the definition provided by Wikipedia:
The MaxDiff is a long-established academic mathematical theory with very specific assumptions about how people make choices: it assumes that respondents evaluate all possible pairs of items within the displayed set and choose the pair that reflects the maximum difference in preference or importance. It may be thought of as a variation of the method of Paired Comparisons. Consider a set in which a respondent evaluates four items: A, B, C and D. If the respondent says that A is best and D is worst, these two responses inform us on five of six possible implied paired comparisons:
A > B, A > C, A > D, B > D, C > D
The only paired comparison that cannot be inferred is B vs. C. In a choice among five items, MaxDiff questioning informs on seven of ten implied paired comparisons.
This Askia Design Control allows you to easily create the required screen format for MaxDiff surveys. Add the ADC to your resources, drag it on to your Most response block, set any captions you want to appear in the headers of your grid and select the Least question it should be connected to. As with most ADCs, this survey control allows you to customise many parameters, such as:
- Least Question: when you drag the ADC on to the response block for your ‘Most’ question, this is where you define which ‘Least’ question it relates to.
- Most Caption: the caption you want to appear in the ‘Most’ column header.
- Least Caption: the caption you want to appear in the ‘Least’ column header.
- Centre Caption: the caption you want to appear in the centre column header e.g. this can be information about the loop iteration or screen number.
You can play around with this survey control in the following demos:
Alternatively, you can download (or even contribute) the MaxDiff ADC from Github!
MaxDiff interactive library
When conducting MaxDiff methodology you have a number of different parameters to consider and produce programming instructions for. At Askia, we have used the R software environment to do this for the different parameters and a large range of the options for each. We have created an interactive library in Design which asks you what option you want for each parameter. The result is a greatly simplified process for producing any MaxDiff design with Askia.
The available parameters are:
- Number of questions: also known as the number of arrangements or number of screens. This is the number of screens the respondent will see during the course of the MaxDiff section.
- Number of selectable items: this is the number of options to choose between per screen.
- Number of items: this is the number of attributes or statements you want to include overall in the MaxDiff design.
Check out the full article for more in-depth information & resources.
As we have seen in the above, the key point with standard MaxDiff is that the arrangements on screen are pre-set and do not adapt to the responses given in interview. In addition, the number of selectable options on screen is a constant.
However, in adaptive MaxDiff, the number of selectable options will change. Each round of screens, the items selected as Least are removed from the next round of screens. The number of items on screens therefore diminishes until you get to the start of the last round where you are asked to pick between all those you chose as Most.
The advantages of adaptive MaxDiff are that greater discrimination between items of importance is achieved. The disadvantages? Well, it could be argued that, since your initial answers create the upcoming arrangements, you do not have as much opportunity to change your mind about items you have rated least important in previous rounds.
This article details these differences, provides an example questionnaire to showcase the setup of this methodology with Askia as well as instructions on using and updating the example file for your own list of items.