docs, news

Author: strengejacke

NEWS.md

@@ -6,6 +6,9 @@
   functions provide information about the reliability of group-level estimates
   (i.e., random effects) in mixed models.
 
+* `check_group_variation()` to check whether variables have a within- or between-
+  group variation (or both).
+
 ## Changes
 
 * Singularity checks with `check_singularity()` are now more efficient and also

R/check_group_variation.R

@@ -26,6 +26,10 @@
 #'   the data is treated as cross-classified. Only applies if `by` contains more
 #'   than one variable.
 #'
+#' @return A list with at most three elements, `within`, `between`, and `both`,
+#' where each element contains the name of variables that have one of these
+#' effects.
+#'
 #' @examples
 #' set.seed(1234)
 #' dat <- data.frame(