|Summary||When conducting MaxDiff methodology you have a number of different parameters to consider and produce rotations (programming instructions) for. Here at askia we have used the R software package 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 in askia.|
|Applies to||askiadesign 5.4.6 and above|
|Written for||Scriptwriters and survey authors, Statisticians.|
|Keywords||design; askiadesign; library; template; automatic; generation; survey; MaxDiff.|
Background and other articles:
There are a few articles already on our Help Centre regarding MaxDiff & Interactive Library. It will be useful to have reviewed these first.
- Design: Example of MaxDiff methodology
- Analyse: Basic analysis of MaxDiff data
- Design: Interactive libraries in Design 5.4
- Design: MaxDiff Table ADC
Saving an example interactive library file:
- Download the example .qex
- Open the example .qex in Design 5.4.6 or above
- Select all questions from the question tree on the left, then right click and select "add to the local library".
- Give it a name. You can now re-use this template to produce new MaxDiff Designs.
The parameters explained:
- Number of questions (Range: 11 - 58)
- 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. In the example below we have 11.
- Number of selectable items (Range: 3 - 5)
- This is the number of options to choose between per screen - in the screenshot below, we have three.
- Number of items (Range: 15 - 80)
- This is the number of attributes or statements you want to include overall in the MaxDiff design. In the example below we have 16.
The number of questions/screens (QS) is tied to the number of items/attributes (IA) by way of the following expression:
QS ≥ floor(⅔(IA)+1)
This is an area of statistical discussion and the above is cited as a good standard for producing a statistically robust rotation of all items/attributes.
Using the R software package we run the required syntax to produce the rotation matrices that will be set into the Matrix loop items shown in the first screenshot above. We run the expression above until: QS = floor(⅔(IA)+5). It is important to note the numeric relationship between Questions & Items when using the MaxDiff Interactive library because if you choose a number of items or questions that do not correspond to the expressions above, you will be missing code-frames in one or more of your questions. I have uploaded a quick solution for checking what corresponding questions/screens vs items/attributes selections are allowed. Click here to access the Excel checking table.
How the parameters are arranged in the interactive library file:
Using the interactive library file to create a new MaxDiff design:
In Design, right click in the question tree and select 'Library', select the MaxDiff Interactive library you added earlier from the drop-down list and then enter your number of questions/screens, number of selectable items per screen and finally the number of items/attributes overall. For the final screen you can enter the items/attributes manually or by copy/pasting in the whole list from elsewhere e.g. Excel.
Take a look at the .gif below to see these steps in practice:
Using the new MaxDiff ADC to easily create the screen layout:
Once you have created your new MaxDiff Design you'll note that the screens need some work to get them into the correct format (see second screenshot in this article). Up until recently this had been a tedious process. However, we have now introduced a MaxDiff ADC to take care of this for you. You 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.
Take a look at the .gif below to see these steps in practice and the final result:
The ADC page on our Help Centre is here.