Updated description of parameters in P/NBD

R/f_interface_pnbd.R

@@ -23,6 +23,9 @@
 #' The smaller r, the stronger the heterogeneity of the purchase process.\cr
 #' \code{alpha}: scale parameter of the Gamma distribution of the purchase process.
 #'
+#' Based on these parameters, the average purchase rate while customers are active
+#' is r/alpha and the average dropout rate is s/beta.
+#'
 #' Ideally, the starting parameters for r and s represent your best guess
 #' concerning the heterogeneity of customers in their buy and die rate.
 #' If covariates are included into the model additionally parameters for the