what is the difference between a fixed factor and a mixed effects model? how can i test my hypothesis using a mixed effect model using spss? spss how to model a mixed effect can I use a fixed-factor variable in mixed-effects how to test mixed effects with time do mixed effects models include a fixed factor if the drug x has a fixed slope what is the significance of this change when is mixed effects data normal if medication x increases duration of headache, what does that mean can you use random variables to compare treatment conditions which is more appropriate to use mixed-effects or random-initiated models? ___________ should be a fixed factor and time points are a covariate based variable. why is time period a fixed factor why is it necessary to model for a complication of a mixed effect why is the time intervals of a mixed effect study a fixed factor what is a mixed effect model for headaches how do i test a mixed effect model in spss when to use mixed model in phsd what type of data is mixed effect how do you use a mixed-effects model