Factor codings in linear mixed models (GAMLj3)

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lenaheffner
Posts: 3
Joined: Thu Jul 18, 2024 5:08 pm

Factor codings in linear mixed models (GAMLj3)

Post by lenaheffner »

Hi everyone,

I´d like to calculate a linear mixed model.
Mine contains several factors and I am asked to choose their coding.

I did dummy-code them manually before I imported the dataset into Jamovi, as I was not aware this is possible in Jamovi.

How can I specify that I do not want them to be coded in any additional way?
I found "custom" in the dropdown menu, but what do I need to write there? Just leave it blank?


It would be a pity to need to start again from scratch...

Thanks a lot! :-)
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mcfanda@gmail.com
Posts: 562
Joined: Thu Mar 23, 2017 9:24 pm

Re: Factor codings in linear mixed models (GAMLj3)

Post by mcfanda@gmail.com »

In "factors coding" panel you find all the coding available, including "dummy", although I doubt that you really need dummy coding.

If you want to use the exact coding in data, simply put your dummy variables in "covariates". However, in this way you loose the omnibus tests for factors with more than 2 levels (and a lot of other facilities offered by the module for categorical independent variables).

The recommended method is to define categorical variables as factors and choose the coding system that better suites you

The coding systems are described here https://gamlj.github.io/rosetta_contrasts.html
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