Description

The mads object contains an amputed data set. The mads object is generated by the ampute function. The mads class of objects has methods for the following generic functions: print, summary, bwplot and xyplot.

Contents

call:

The function call.

prop:

Proportion of cases with missing values. Note: even when the proportion is entered as the proportion of missing cells (when bycases == TRUE), this object contains the proportion of missing cases.

patterns:

A data frame of size #patterns by #variables where 0 indicates a variable has missing values and 1 indicates a variable remains complete.

freq:

A vector of length #patterns containing the relative frequency with which the patterns occur. For example, if the vector is c(0.4, 0.4, 0.2), this means that of all cases with missing values, 40 percent is candidate for pattern 1, 40 percent for pattern 2 and 20 percent for pattern 3. The vector sums to 1.

mech:

A string specifying the missingness mechanism, either "MCAR", "MAR" or "MNAR".

weights:

A data frame of size #patterns by #variables. It contains the weights that were used to calculate the weighted sum scores. The weights may differ between patterns and between variables.

cont:

Logical, whether probabilities are based on continuous logit functions or on discrete odds distributions.

type:

A vector of strings containing the type of missingness for each pattern. Either "LEFT", "MID", "TAIL" or "RIGHT". The first type refers to the first pattern, the second type to the second pattern, etc.

odds:

A matrix where #patterns defines the #rows. Each row contains the odds of being missing for the corresponding pattern. The amount of odds values defines in how many quantiles the sum scores were divided. The values are relative probabilities: a quantile with odds value 4 will have a probability of being missing that is four times higher than a quantile with odds 1. The #quantiles may differ between patterns, NA is used for cells remaining empty.

amp:

A data frame containing the input data with NAs for the amputed values.

cand:

A vector that contains the pattern number for each case. A value between 1 and #patterns is given. For example, a case with value 2 is candidate for missing data pattern 2.

scores:

A list containing vectors with weighted sum scores of the candidates. The first vector refers to the candidates of the first pattern, the second vector refers to the candidates of the second pattern, etc. The length of the vectors differ because the number of candidates is different for each pattern.

data:

The complete data set that was entered in ampute.

Note

Many of the functions of the mice package do not use the S4 class definitions, and instead rely on the S3 list equivalent oldClass(obj) <- "mads".

Author(s)

Rianne Schouten, 2016

See Also

ampute, Vignette titled "Multivariate Amputation using Ampute".