In the very first chunk of code part of the solution is to state “I observe that there are no missing values other than those indicated by Group NA for occupation.”
How are we supposed to observe this? the summary and str functions do not show us this. There is no unique() function used to see all entries. is.na() would not have worked. we can use head(df) or even just df but we can only view so many lines so that does not guarantee we would have seen this.
What should bring the test taker to the conclusion that there are no missing values? How are we supposed to know their is a “Group NA” in the data set using the chunk of code provided?