Using bal.tab() with Subclassified Data
When using bal.tab()
with subclassified data, i.e., data split into subclasses where balance may hold, the output will be different from the standard, non-subclassified case, and there is an additional option for controlling display. This page outlines the outputs and options in this case.
There are two main components of the output of bal.tab()
with subclassified data: the balance within subclasses and the balance summary across subclasses. The within-subclass balance displays essentially are standard balance displays for each subclass, except that only "adjusted" values are available, because the subclassification itself is the adjustment.
The balance summary is, for each variable, like a weighted average of the balance statistics across subclasses. This is computed internally by assigning each individual a weight based on their subclass and treatment group membership and then computing weighted balance statistics as usual with these weights. This summary is the same one would get if subclasses were supplied to the match.strata
argument rather than to subclass
. Because the means and mean differences are additive, their computed values will be weighted averages of the subclass-specific values, but for other statistics, the computed values will not be.
There are three arguments for bal.tab()
that relate to subclasses: subclass
, which.subclass
, and subclass.summary
.
subclass |
For the |
which.subclass |
This is a display option that does not affect computation. If |
subclass.summary |
This is a display option that does not affect computation. If |
The output is a bal.tab.subclass
object, which inherits from bal.tab
. It has the following elements:
Subclass.Balance |
A list of data frames containing balance information for each covariate in each subclass. |
Balance.Across.Subclass |
A data frame containing balance statistics for each covariate aggregated across subclasses and for the original sample (i.e., unadjusted). See |
Noah Greifer
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