dist: A distribution function. This argument takes a quoted R distribution function (e.g. 'rnorm'). Default is 'rnorm'.
var_level: The level the variable should be simulated at. This can either be 1, 2, or 3 specifying a level 1, level 2, or level 3 variable respectively.
variance: The variance for random effect simulation.
ther_sim: A TRUE/FALSE flag indicating whether the error simulation function should be simulated, that is should the mean and standard deviation used for standardization be simulated.
ther_val: A vector of 2 that should include the theoretical mean and standard deviation of the generating function.
...: Additional parameters to pass to the dist_fun argument.