parameter_estimates: (array) Parameter estimates for parameters to use
fraction: (numeric) Fraction of estimate value to use for distribution bounds
force_posdef_samples: (numeric (optional)) Number of samples to reject before forcing variability parameters to give positive definite covariance matrices.
n: (numeric) Number of samples
seed: (numeric (optional)) Random number generator or seed
scale: (str) Scale to perform sampling on. Valid options are 'normal' and 'UCP'