There seems to be a fair amount of redundancy in the tags containing imputation in them. As of this writing, I observe the following distribution of imputation tag usages:
data-imputation: 160
multiple-imputation: 617
imputation: 4
Clearly multiple imputation is just one (very popular) variety of imputation, so perhaps we only need the tags imputation and multiple-imputation. To me, data-imputation appears to be somewhat redundant: I don't know what one would impute if not data!