The Advanced MaxDiff test is a great way to compare many alternatives without overwhelming respondents by asking them to read and consider all items at once. It takes a list of your items to be compared, and shows them in a balanced order to each respondent 4 at a time.
The method is focused on collecting general aggregate information, without the intention to obtain individual-level estimates. In typical settings respondents would see 3-5 screens.
In deciding which items to show on the next screen of the MaxDiff, the system focuses on ensuring equal coverage of pairs of items among all respondents. In other words, items are chosen randomly, with bias toward pairs of items that were seen less frequently overall across respondents.
The core analysis of respondents' preferences is performed by Maximum Likelihood Multinomial Logit model.
The statistics page has three display modes:
- Raw coefficients mode - aggregation of zero-minimized raw Logit coefficients. Score of 0 means the item was least preferred compared to all other items. The larger the score, the more preferable the item was.
- Average probabilities mode - aka Probability of Choice - probability of this item being selected in an exercise with two items, the second item being an average item.
- Max Diff Scale % mode - is the average probabilities mode scaled down so that sum of probabilities equals 100%.
- Raw coefficients export: zero-centered Logit coefficients for each respondent
- Raw data Export: data on what each respondent saw, and what decision was made on each task