The meetings are organized by Enrico Toffalini and Tommaso Feraco in partnership with the PsicoStat group
22nd of March, 2023
Gianmarco Altoè: Logistic regression (and generalized linear models in Psychology)
Very often, response variables in psychology are not generated by Normal distributions, which leads to fundamental violations of the assumptions needed for linear models. Luckily, GLMs (generalized linear models) are available for most situations in which responses are known to be non-normal. Among them, logistic regression is especially important as it allows us to model probabilities for binomial 0 / 1 data (e.g., the probability of observing correct responses as a functions of predictors in an experiment).
Click here to see the slides (22/03/2023)
(Also, see this very important series of slides by prof. Altoè on generalized linear mixed-effects models)
8th of March, 2023
Practical Exercises on Linear Mixed Models
Click here to see the slides (08/03/2023)
Click here to download the datasets for the exercises (08/03/2023)
22nd of February, 2023
Introduction to Linear Mixed Models
Linear mixed models (LMM) arguably represent the ideal framework for data analysis in most actual research scenarios in psychology. LMM are more flexible and they extract more information from data than common alternatives when they are used to their full potential. When their logic is understood, they are also a powerful aid in the phase of planning new research.
Click here to see the slides (22/02/2023)
Click here to download the R code (22/02/2023)
15th of February, 2023
The “for” loop, and how to run power analysis with simulated data for simple linear models
Once the basics facts about coefficients of linear models are understood (see first two meetings), it’s time to run a power analysis. The “for” loop is an intuitive tool for running power analysis using simulated data. In fact, power could be calculated analytically for simple cases, but understanding how to use simulation and the “for” loop opens the way to applying it to more complex scenarios as well. The cases we see here involve basic simple and multiple linear regression models.
Click here to download the slides and R code (15/02/2023)
18th of January + 1st of February, 2023
Coefficients in linear models, interactions, model comparisons, and data simulation
Understanding coefficients in linear models is the starting point for many more complex skills in data analysis. In the first two meetings of this workshop on data analysis, we discussed the interpretation of linear model coefficients in a series of cases featuring models with main effects, with interactions between two category variables and interactions between a continuous and a category variable. Also, we briefly discussed model comparisons and we started practicing some data simulation for the purpose of performing power analysis in the next meeting(s).
Click here to download the slides and R code of the first meeting (18/01/2023)
Click here to download the slides and R code of the second meeting (01/02/2023)