Workshop on common issues and standard in ordinary and multilevel regression modeling
March 25, 2009, UC Davis
Goal of this workshop
in progress
Common issues in regression modeling and some solutions
Maybe develop cheat sheet? with step-by-step guidelines of some things one should make sure to do when developing a model? does baayen or harell have something like this?
- common issues in regression modeling
- o collinearity o overfitting o overly influential cases o overdispersion? o model quality (e.g. residuals for linear models) o building a model: adding/removing variables (also: interactions)
- some solutions to these problems for common model types
- o outlier handling o centering o removing collinearity (e.g. PCA, residualization) o stratification (using subsets of data)
- interpreting the model, making sure the model answers the question of interest:
- o testing significance (SE-based tests vs. model comparison) o interpration of model output, e.g. interpreation of coefficients o (also: coding of variables) o follow-up tests
Some suggestions on how to present model results
What do readers need to know?
What do reviewers need to know?
- How to talk about effect sizes?
- absolute coefficient size (related to range of predictor) -- talking about effect ranges.
- relative coefficient size (related to its standard error)
- model improvement, partial R-square, etc.
- accuracy?
- How to back-translated common transformations of outcomes and predictors?
Written description of the model
Visualization