# micombine.chisquare: Combination of Chi Square Statistics of Multiply Imputed... In miceadds: Some Additional Multiple Imputation Functions, Especially for 'mice'

## Description

This function does inference for the χ^2 statistic based on multiply imputed datasets (see e.g. Enders, 2010, p. 239 ff.; Allison, 2002). This function is also denoted as the D_2 statistic.

## Usage

 1 micombine.chisquare(dk, df, display=TRUE, version=1)

## Arguments

 dk Vector of chi square statistics df Degrees of freedom of χ^2 statistic display An optional logical indicating whether results should be printed at the R console. version Integer indicating which calculation formula should be used. The default version=1 refers to the correct formula as in Enders (2010), while version=0 uses an incorrect formula as printed in Allison (2001). The incorrect calculation version=0 was included in miceadds versions smaller than version 2.0. See also http://statisticalhorizons.com/wp-content/uploads/2012/01/combchi.sas.

## Value

A vector with following entries

 D Combined D_2 statistic which is approximately F-distributed with (df, df2) degrees of freedom p The p value corresponding to D df Numerator degrees of freedom df2 Denominator degrees of freedom

## References

Allison, P. D. (2002). Missing data. Newbury Park, CA: Sage.

Enders, C. K. (2010). Applied missing data analysis. Guilford Press.

See also mice::pool.compare for a Wald test to compare two fitted models in the mice package.

## Examples

 1 2 3 4 5 6 7 8 9 10 ############################################################################# # EXAMPLE 1: Chi square values of analyses from 7 multiply imputed datasets ############################################################################# # Vector of 7 chi square statistics dk <- c(24.957, 18.051, 18.812, 17.362, 21.234, 18.615, 19.84) dk.comb <- miceadds::micombine.chisquare(dk=dk, df=4 ) ## Combination of Chi Square Statistics for Multiply Imputed Data ## Using 7 Imputed Data Sets ## F(4, 482.06)=4.438 p=0.00157

### Example output

Attaching package: 'mice'

The following objects are masked from 'package:base':

cbind, rbind