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An optimal cluster-based approach for Subgroup Analysis using Information Complexity Criterion.
The global imbalance (GI) measure is a way for checking balance of baseline covariates
that confound eorts to draw valid conclusions about treatment eects on outcomes
of interest. In addition, GI is tested by means of a multivariate test. The GI measure
and its test overcome some limitations of the common way for assessing the presence of
imbalance in observed covariates that were discussed in D'Attoma and Camillo (2011).
A user written SAS macro called %GI, to simultaneously measure and test global imbalance
of baseline covariates is described. Furthermore, %GI also assesses global imbalance
by subgroups obtained through several matching or classication methods (e.g., cluster
analysis, propensity score subclassication, Rosenbaum and Rubin 1984), no matter how
many groups are examined. %GI works with mixed categorical, ordinal and continuous
covariates. Continuous baseline covariates need to be split into categories. It also works in
the multi-treatment case. The use of the %GI macro will be illustrated using two articial
examples