In general, if you want to map an aesthetic to a variable and get a legend in ggplot2 you do it inside aes(). If you want to set an aesthetic to a constant value, like making all your points purple, you do it outside aes(). However, there are situations where ...

One of the things I like about simulations is that, with practice, they can be a quick way to check your intuition about a model or relationship. My most recent example is based on a discussion with a student about quadratic effects. I’ve never had a...

I first learned how to check for autocorrelation via autocorrelation function (ACF) plots in R in a class on time series However, the examples we worked on were all single, long term time series with no missing values and no groups. I figured out later...

I’ve done a couple of posts so far on simulations, here and here, where I demonstrate how to build a function for simulating data from a defined linear model and then explore long-run behavior of models fit to the simulated datasets. The focus of those posts was on the ...