IBM Data and AI

Welcome to the IBM Data and AI Ideas Portal for Clients!

We welcome and appreciate your feedback on IBM Data and AI Products to help make them even better than they are today!
Before you submit an idea, please perform a search first as a similar idea may have already been reported in the portal. If a related idea is not yet listed, please create a new idea and include with it a description which includes expected behavior as well as why having this feature would improve the service and how it would address your use case.
IBM Employees:
  • Our team welcomes any feedback and suggestions you have for improving our offerings / products! This forum allows us to connect your offering / product improvement ideas with IBM product and engineering teams.

  • If you have not registered on this portal please click on the following link and register. To complete registration you will need to open the email you will receive from Aha to confirm your identity.

Additional Information:
  • The shorter URL for this site is:

  • To view our roadmaps:

  • Reminder: This is not the place to submit defects or support needs, please use normal support channel for these cases

  • Please do not use the Ideas Portal for reporting bugs - we ask that you report bugs or issues with the product by contacting IBM support.

Save the Random Effects of Mixed/Multilevel Models

Mixed/multilevel models are used to analyze hierarchical data (e.g., repeated-measures data, “nested” data such as when data is collected from individuals working in teams). Mixed models are able to disentangle variance that occurs among the lowest level of observations (e.g., differences between measurements repeatedly collected from the same person, differences between individuals working together in a team) from variance that occurs at higher levels of observation (e.g., differences between the people from whom measures were repeatedly collected, differences between the teams in which people are working). Mixed models achieve this by estimating a different intercept and/or slope(s) for each higher-level group. These per-group intercept and slope estimates are called “random effects.”

I am requesting that SPSS provide a new keyword on the SAVE subcommand of the MIXED procedure that will save all the random effects of a multilevel model in a new dataset. Other statistical programs can easily save random effect estimates, and the SPSS MIXED procedure is estimating these random effects when running the MIXED procedure, anyway.

Currently, there is a way to derive one set of random estimates in SPSS from mixed models that have only one random effect (e.g., only a random intercept). To do this, you save the fixed predicted values and the random predicted values and use the difference between them to back-infer the random estimates for each group. However, this only works if you are modeling one random effect (e.g., one random slope with no random intercept). Most of the time, researchers who want to save random slopes are also estimating random intercepts to account for mean differences between their groups, so this hack is insufficient. Moreover, even when a model only estimates one random effect, it would be nice if researchers could simply save the random effect through the SAVE subcommand without needing to calculate it from the predicted values.

Please note that this request applies to the MIXED procedure on any operating system. The requested feature form required me to select one operating system when submitting this request, so I selected Windows because it is common among SPSS users.
  • Avatar32.5fb70cce7410889e661286fd7f1897de Guest
  • Dec 14 2018
  • Delivered
Idea Priority High
Customer Name University of Toronto
  • Attach files

NOTICE TO EU RESIDENTS: per EU Data Protection Policy, if you wish to remove your personal information from the IBM ideas portal, please login to the ideas portal using your previously registered information then change your email to "anonymous@euprivacy.out" and first name to "anonymous" and last name to "anonymous". This will ensure that IBM will not send any emails to you about all idea submissions