What is the differeence between individual parameter and offset parameter?

[zaizibai]

Dear HSSM developers and DDM/SSM experts,

Thank you for developing this wonderful package. I’m currently fitting a standard DDM to data from a Stroop task and had a question regarding individual-level parameters when including random slopes in the model.

I noticed that, when random slopes are included, there appear to be two types of individual parameters: one with an offset and one without. Could you please clarify the difference between the two? Which version should be used to interpret the “true” individual parameters?

Thanks a lot,
Mingqian