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.
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.
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?