Say that we have a cross-sectional dataset with two variables, A and B.
Also suppose that A and B are related to each other in some way. Now, there are some rows for which only A is missing, and some for which only B is missing. There are no rows for which both A and B are missing.
Now say that I want to impute these missing values by just taking the average of A and the average of B.
Would this be problematic, given that A and B are related to each other?