Fixed Effects vs Random Effects Models

What is a fixed effects model? What is a random effects model? What is the difference between them? Many people around me have been using these terms over and over in the past few weeks. I finally compiled several 5-10 min videos of people answering these questions well online.

IndianJDermatol_2014_59_2_134_127671_f3_Vertical

If I had to answer the question of what fixed and random effects models are in one image, I would choose this one from the Indian Journal of Dermatology. Watch the videos and come back to this image for a quick reminder of these concepts.


Motivating Example: Meta-Analysis of Bieber Fever

This silly example is a simplistic demonstration of when fixed and random effects models should be used in designing a meta-analysis. This video is for the medical student.


Summary of Fixed and Random Effects Models

This summary video is a bit more technical and is aimed at a student of epidemiology or biostatistics.


What is Heterogeneity?

The concept of heterogeneity kept coming up in these videos. How is it different from random chance? This is a clear explanation of the difference that defines concepts alluded to in the previous videos.


Sources

Indian Journal of Dermatology: Understanding and evaluating systematic reviews and meta-analyses

Brian Cohn: Fixed and Random Effects Models and Bieber Fever

Terry Shaneyfelt: Fixed Effects and Random Effects Models

Terry Shaneyfelt: What is Heterogeneity?

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