Intro to mixed models

Content

• Fixed vs random effects
• Blocking factors
• Introduction to linear mixed models

Learning objectives

At the end of the session, students should be capable of

• determining the structure of an experimental design with random and fixed effects
• correctly determining whether effects are crossed or nested
• correctly analyzing models with blocking factors
• setting up a linear mixed model

Readings

• Chapter 5 (Complete Block Designs) of Meier (2022) (5.1-5.2)
• Chapter 6 Random and Mixed-Effects Models of Meier (2022)
• Chapter 12 of the course notes

Complementary readings

• Chapter 4 of Cox (1958).
• Chapters 10 and 15 of Maxwell et al. (2017).

Slides

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Code

• R script
• SPSS script

Tip

Fun fact: If you type ? (or shift + /) while going through the slides, you can see a list of slide-specific commands.

References

Cox, D. R. (1958). Planning of experiments. Wiley.

Maxwell, S. E., Delaney, H. D., & Kelley, K. (2017). Designing experiments and analyzing data: A model comparison perspective (3rd ed.). routledge. https://doi.org/10.4324/9781315642956

Meier, L. (2022). ANOVA and mixed models: A short introduction using R (Chapman & Hall/CRC, Eds.). https://doi.org/10.1201/9781003146216