Linear Mixed Methods on SPSS

A simplified overview of how to perform a linear mixed methods analysis on SPSS.

[@purblancas]

But you didn't use a random effect. Why not use multiple linear regression with fixed effects?

[@LauraVossen]

Because in this data the same patient appears several times in your model, violating the independency of errors assumption of ANOVA. Therefore you need to use either repeated measures ANOVA or build a mixed-effects model.

[@rekabuzassy4496]

Hi, can you help me with my analysis?
I have the following conceptual model:
IV: Personality trait (measured on likert scale)
Moderator: low trust vs high trust (binary: 1/2)
DV: initial price offer in a negotiation ( values can be between 5-15, repeated measures)
I have a within-subjects design, so first i assessed the personality of the respondent, then each respondent was asked to input an offer given the scenario (scenario1: low trust towards their negotiation partner). Then in a secod scenario (scenario2: higher trust towards their negotiation partner) they had to input a second offer.
I organiyed my data like this:
id scenario dv trait
1 1 3 3.33
1 2 2 3.33
2 1 5 4.11
2 2 1 4.11
...
I want to measure the effect of personality on the initial offer and how this relationship is moderated by the level of trust.
What should be my subject, and my fixed effect? I am not sure where to indluce personality trait in this model.