NAs
Summary

Instruction

You're making excellent progress! What about the summary() function? Fortunately for us, the summary() function automatically removes NAs by default, so you don't have to worry about specifying anything for na.rm on your end.

For example, given the call to

summary(houses$yard_area)
R will calculate various summary statistics without NAs. As a bonus, it will also tell you how many NA values were encountered!

Here's what the output of summary() looks like:

Min.   1st Qu.   Median    Mean   3rd Qu.    Max.  NA's
 0.0     196.2    385.0   567.7     561.5  5500.0     8

Exercise

The data set houses has a column named last_renovation, and some of its values are missing. Calculate summary statistics for this column, and observe the result. How many values are missing from this column?