I have this huge data set with like 2500 variables and like 142 observations. 

I want to run a correlation between Variable X and the rest of the variables. But for many columns, there are entries missing. 

I tried to do this in R using "pairwise-complete" argument (`use=pairwise.complete.obs`) and it outputted a bunch of correlations. But then someone on StackOverflow posted a link to this article <http://bwlewis.github.io/covar/missing.html> and it makes the "pairwise-complete" method in R look unusable. 

**My Question: How do I know when it is appropriate to use "pairwise-complete" option?**

My `use = complete.obs` returned `no complete element pairs`, so if you could explain what that means too, that would be great.