data: a PROsetta_data object. See loadData for loading a dataset.
estimator: the estimator to be used. Passed onto cfa in 'lavaan' package. (default = WLSMV)
std.lv: if TRUE, the metric of the latent variable is determined by fixing their (residual) variances to 1.0. If FALSE, the metric of each latent variable is determined by fixing the factor loading of the first indicator to 1.0. Passed onto cfa. (default = TRUE)
scalewise: if TRUE, run analysis for each instrument as well as for the combined instrument. If FALSE, run analysis only for the combined instrument. (default = FALSE)