manage_missing
deals with the imputation of missing values in the elementary indicators.
It is an internal function.
Arguments
- data
data matrix of elementary indicators (as returned by
create_indicator_matrix()
).- missing
method for imputing missing values:
missing = 0
: missing values are replaced with '0' (not at risk);missing = 1
: missing values are imputed using logistic regression. See Details.
- verbose
whether a summary of imputed values has to be printed (when
missing = 1
).- seed
seed for the random draw from a Bernoulli r.v. (when
missing = 1
). See Details.
Details
When missing = 1
, elementary indicators are split up into two groups, according to
the presence/absence of (at least one) missing values. Hence, the set of indicators without
missing values (taken as covariates) is used to 'predict' the missing values in each of the other
indicators (seen as dependent variable), using several logistic regression models, one for each
indicator with missing values. As such, these models can predict a probability for each combination
of observed indicators; then, a random draw from a Bernoulli distribution with the predicted
probability as parameter is performed for imputing '0' or '1' in the indicator with missing values.