roughout this book. The DGP contains everything of importance when considering the variability of the data in the context of other data that could have been collected. This includes how subjects were sampled (e.g., if we randomly sample octopuses then other possible data sets would contain data from other octopuses), how subjects are assigned to conditions (if any), but most importantly also how subjects generate responses (or otherwise observable events), and any possible source of randomness in this gener