diff --git a/transform.Rmd b/transform.Rmd
index acb2c8b..6ae1c6e 100644
--- a/transform.Rmd
+++ b/transform.Rmd
@@ -773,7 +773,7 @@ Just using means, counts, and sum can get you a long way, but R provides many ot
     # What proportion of flights are delayed by more than an hour?
     not_cancelled %>% 
       group_by(year, month, day) %>% 
-      summarise(hour_perc = mean(arr_delay > 60))
+      summarise(hour_prop = mean(arr_delay > 60))
     ```
 
 ### Grouping by multiple variables