SPSS Statistics

Expand all | Collapse all

Parameter estimates of fixed effects in multilevel analysis with interactions

  • 1.  Parameter estimates of fixed effects in multilevel analysis with interactions

    Posted Tue September 21, 2021 12:52 PM
      |   view attached
    Hello, 

    We conducted an experiment with a 2 x 2 x 4 design, where the first 2 factors are within-subjects and the third factor was manipulated between-subjects. 
    As fixed effects, I included the three factors, the two-way interactions and the three-way interaction. 
    As random effect, I included the participant ID (and intercept). 

    The results in the 'type III tests of fixed effects' table seem to be correct, and correspond with the results I get from a repeated measures ANOVA. 
    However, the results from this table do not correspond with the 'parameter estimates of fixed effects' in the output. 
    I know that this is because I added interactions to the model. The first table (type III tests) reports main effects, while the second table (parameter estimates) reports simple effects.These simple effects are influenced by the higher order effects of the interactions. So, adding interactions changes the parameter estimates for the three manipulations. 

    I was wondering whether there is a possibility to change this so that the parameter estimates do correspond with the results from the type III fixed effects table? I don't want to exclude my interactions, because they are important elements in the model. For instance, could I add something to the /TEST field in the syntax?

    ------------------------------
    Lotte Hallez
    ------------------------------


  • 2.  RE: Parameter estimates of fixed effects in multilevel analysis with interactions

    Posted Tue September 21, 2021 04:13 PM
    Hi. I'm no expert in this kind of modeling so perhaps I'm misunderstanding but what if you were to specify in your /FIXED subcommand:
    
    MIXED ...
      /FIXED=color claim product_set color*claim color*product_set claim*product_set color*claim*product_set | SSTYPE(3)
    ​

    When I do that, the Fixed Effects parameter table includes the non-redundant estimates for each effect in the Type III Tests table:



    ------------------------------
    Rick Marcantonio
    Quality Assurance
    IBM
    ------------------------------