Missing data - Margin plot interpretation

I've been having my doubts on the topic of interpretation of margin plots for missing data.

Package VIM provides with the margin function that outputs the following graph:


Basically it displays the distribution of one variable's missing data in the other variable (Red) and the distribution of non-missing data as well (blue).

My current decision rule is the following:

  • If the distribution of missing data matches the distributions of non-missing data it means that I can use one variable to input the other.

  • However, if the distributions are different (Var2 in the image), I could not use the other variable (Var1) to input values of the first (Var1). If I did so I would be extrapolating predictions.

  • If the missing data in Var2 is also Missing in Var1 (as it is on the image) I can't use Var2 to input Var1 because the missing data could be MNAR, and in such case, I would be over (or under) estimating the inputted values.

I'm concerned as to whether these decision rules are precise or not.

You might try to refer to mine (although the study in Chinese langauge, but the coding in English and output in numeric). I use imputeTS, tidyr and Amelia package.