Run mice iteration-by iteration to compute convergence parameters

[hanneoberman]

Think about applying it to the completed data matrix or the imputed values. Because there is no variance-covariance matrix of the imputations, just correlations. The estimates will be more realistic (compared to the population) for the completed data. If you have too few missing cases, using the imputations results in unreliable estimates, but using the completed data may lead to missing the non-convergence.