In fixed-effects models (e.g., regression, ANOVA, generalized linear models), there is only one source of random variability. This source of variance is the random sample we take to measure our variables.
It may be patients in a health facility, for whom we take various measures of their medical history to estimate their probability of recovery. Or random variability may come from individual students in a school system, and we use demographic information to predict their grade point averages.
If you are new to using generalized linear mixed effects models, or if you have heard of them but never used them, you might be wondering about the purpose of a GLMM.
Mixed effects models are useful when we have data with more than one source of random variability. For example, an outcome may be measured more than once on the same person (repeated measures taken over time).
When we do that we have to account for both within-person and across-person variability. A single measure of residual variance can’t account for both.
There are multiple ways to interface with R. Some common interfaces are the basic R GUI, R Commander (the package “Rcmdr” that you use on top of the basic R GUI), and RStudio.
When I first started to learn to use R, I was bound and determined to use the basic R GUI.
As someone who was already used to programming in SAS, I wasn’t looking for a (more…)
If you are like I was for a long time, you have avoided learning R.
You’ve probably heard that there’s a steep learning curve. Or noticed that the available documentation is not necessarily user-friendly.
Frankly, both things are true, to some extent.
The best and worst thing about R is that it is open-source. So there is no single (more…)