The “stan_lmer” Function in R

• Package: rstanarm

• Purpose: Fits a Bayesian linear mixed-effects model using Stan.

• General class: Modeling

• Required argument(s):

• formula: The model formula specifying the response variable and predictors.

• data: The data frame containing the variables in the formula.

• Notable optional arguments:

• chains: The number of Markov chains to run (default is 4).

• iter: The number of iterations for each chain (default is 2,000).

• cores: The number of CPU cores to use for parallel computing.

• Example:

• # Load the rstanarm library
  library(rstanarm)
  
  # Fit a Bayesian linear mixed-effects model
  model <- stan_lmer(Sepal.Length ~ Sepal.Width + (1 | Species), data = iris)
  
  # Print model summary
  summary(model)

• This example demonstrates how to fit a Bayesian linear mixed-effects model using the stan_lmer function from the rstanarm package. The formula specifies the model structure, and the data argument provides the dataset. Optional arguments like chains, iter, and cores can be adjusted for customizing the modeling process.