1 files changed, 7 insertions, 0 deletions
diff --git a/R/idea.R b/R/idea.R
index 14ba838..dad4220 100644
--- a/R/idea.R
+++ b/R/idea.R
@@ -42,6 +42,13 @@
 #' # Obtain R0 when the serial distribution has a mean of three days.
 #' idea(cases, mu = 3 / 7)
 idea <- function(cases, mu) {
+  validate_cases(cases, min_length = 2, min_count = 1)
+  if (!is_real(mu) || mu <= 0) {
+    stop("The serial interval (`mu`) must be a number greater than 0.",
+      call. = FALSE
+    )
+  }
+
   s <- seq_along(cases) / mu
 
   x1 <- sum(s)