Let's have a look at the occupation column now. Sometimes it's difficult to establish someone's occupation; some people don't want to share it. So why don't we see any NA values?
Remember, we have data that looks like this:
[1] Computer Systems Analyst III [2] [3] Sales Associate
The second line is missing, but that is no mistake: it is blank. For R, blank (coded as "") is not the same as NA. We need to change that. We can do this the same way we did with age:
census2017$occupation[census2017$occupation==""] <- NA
In the census2018 data frame, change the coding of missing values in the occupation column from blank ("") to NA.
