diff --git a/DESCRIPTION b/DESCRIPTION
index 986d366..dc8b36a 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: irxforge
 Title: Forging data for pharmacometric analyses
-Version: 0.0.0.9002
+Version: 0.0.0.9003
 Authors@R: c(
     person("Ron", "Keizer", email = "ron@insight-rx.com", role = c("cre", "aut")),
     person("Michael", "McCarthy", email = "michael.mccarthy@insight-rx.com", role = "ctb"),
diff --git a/R/sample_covariates_mvtnorm.R b/R/sample_covariates_mvtnorm.R
index 67aa689..de00e23 100644
--- a/R/sample_covariates_mvtnorm.R
+++ b/R/sample_covariates_mvtnorm.R
@@ -1,8 +1,16 @@
 #' Sample covariates from multivariate normal distributions
 #'
 #' Samples from a multivariate normal distribution either derived from observed
-#' data or specified directly via `means` plus a covariance matrix (`sigma`) or
-#' standard deviations (`sd`).
+#' `data` or specified directly via `means` plus a covariance matrix (`sigma`) 
+#' or standard deviations (`sd`).
+#' 
+#' The `conditional` argument` can be specified only when data is used as input 
+#' (and not with `means` and `sigma or `sd``). If `conditional`` is used in 
+#' conjuction with `data``, it will first downsample the provided dataset to 
+#' include only patients that match the conditional. After that, it will get 
+#' the covariance matrix from the downsampled dataset, and draw samples from 
+#' it. It is therefore possible that, in contrast to e.g. bootstrap sampling, 
+#' samples are drawn that are outside of the min/max given in the conditional.
 #'
 #' @param data data.frame (n x p) containing the original, observed,
 #' time-invariant covariates (ID should not be included) that will be used to
@@ -71,6 +79,9 @@ sample_covariates_mvtnorm <- function(
     if (!is.null(data)) {
       warning("`data` is ignored when `means` is provided.")
     }
+    if(!is.null(conditional)) {
+      warning("`conditional` is ignored when `means` is provided.")
+    }
     if (is.null(sigma) && is.null(sd)) {
       stop("When `means` is supplied, either `sigma` or `sd` must also be provided.")
     }
diff --git a/man/sample_covariates_mvtnorm.Rd b/man/sample_covariates_mvtnorm.Rd
index 201b817..54b8d0a 100644
--- a/man/sample_covariates_mvtnorm.Rd
+++ b/man/sample_covariates_mvtnorm.Rd
@@ -61,8 +61,15 @@ rows and \code{p} columns
 }
 \description{
 Samples from a multivariate normal distribution either derived from observed
-data or specified directly via \code{means} plus a covariance matrix (\code{sigma}) or
-standard deviations (\code{sd}).
+\code{data} or specified directly via \code{means} plus a covariance matrix (\code{sigma})
+or standard deviations (\code{sd}).
+}
+\details{
+The \code{conditional} argument\verb{can be specified only when data is used as input  (and not with}means\code{and}sigma or \verb{sd``). If }conditional\verb{ is used in  conjuction with `data}, it will first downsample the provided dataset to
+include only patients that match the conditional. After that, it will get
+the covariance matrix from the downsampled dataset, and draw samples from
+it. It is therefore possible that, in contrast to e.g. bootstrap sampling,
+samples are drawn that are outside of the min/max given in the conditional.
 }
 \note{
 missing values in \code{data} must be coded as NA