diff --git a/R/wlr.R b/R/wlr.R
index 8c459daa..9d2087f7 100644
--- a/R/wlr.R
+++ b/R/wlr.R
@@ -25,6 +25,17 @@
 #' @param return_variance A logical flag that, if `TRUE`, adds columns
 #'   estimated variance for weighted sum of observed minus expected;
 #'   see details; Default: `FALSE`.
+#' @param ratio randomization ratio (experimental:control).
+#'  - If the `data` is generated by simtrial, such as
+#'    + `data = sim_pw_surv(...) |> cut_data_by_date(...)`
+#'    + `data = sim_pw_surv(...) |> cut_data_by_event(...)`
+#'    + `data = sim_pw_surv(...) |> cut_data_by_date(...) |> counting_process(...)`
+#'    + `data = sim_pw_surv(...) |> cut_data_by_event(...) |> counting_process(...)`
+#'   there is no need to input the `ratio`, as simtrial gets the `ratio` via the
+#'   `block` arguments in [sim_pw_surv()].
+#'  - If the `data` is a custom dataset (see Example 2) below,
+#'    + Users are suggested to input the planned randomization ratio to `ratio`;
+#'    + If not, simtrial takes the empirical randomization ratio.
 #'
 #' @return A list containing the test method (`method`),
 #' parameters of this test method (`parameter`),
diff --git a/man/wlr.Rd b/man/wlr.Rd
index b9249cee..163f8ed9 100644
--- a/man/wlr.Rd
+++ b/man/wlr.Rd
@@ -22,6 +22,24 @@ wlr(data, weight, return_variance = FALSE, ratio = NULL)
 \item{return_variance}{A logical flag that, if \code{TRUE}, adds columns
 estimated variance for weighted sum of observed minus expected;
 see details; Default: \code{FALSE}.}
+
+\item{ratio}{randomization ratio (experimental:control).
+\itemize{
+\item If the \code{data} is generated by simtrial, such as
+\itemize{
+\item \code{data = sim_pw_surv(...) |> cut_data_by_date(...)}
+\item \code{data = sim_pw_surv(...) |> cut_data_by_event(...)}
+\item \code{data = sim_pw_surv(...) |> cut_data_by_date(...) |> counting_process(...)}
+\item \code{data = sim_pw_surv(...) |> cut_data_by_event(...) |> counting_process(...)}
+there is no need to input the \code{ratio}, as simtrial gets the \code{ratio} via the
+\code{block} arguments in \code{\link[=sim_pw_surv]{sim_pw_surv()}}.
+}
+\item If the \code{data} is a custom dataset (see Example 2) below,
+\itemize{
+\item Users are suggested to input the planned randomization ratio to \code{ratio};
+\item If not, simtrial takes the empirical randomization ratio.
+}
+}}
 }
 \value{
 A list containing the test method (\code{method}),