Dealing with missing data

First, let's look at the missing codes for different languages:

For R, the missing code is NA. Here are several functions we could use to remove those missing observations, shown in an example:

> head(na_example,20) 
[1]  2  1  3  2  1  3  1  4  3  2  2 NA  2  2  1  4 NA  1  1  2 
> length(na_example) 
[1] 1000 
> x<-na.exclude(na_example) 
> length(x) 
[1] 855 
> head(x,20) 
[1] 2 1 3 2 1 3 1 4 3 2 2 2 2 1 4 1 1 2 1 2 

In the previous example, we removed 145 missing values by using the R function called na.exclude(). We could...