Specify a matching problem where units in a common factor cannot be matched.Source:
This function builds a distance specification where treated units are infinitely far away from control units that share the same level of a given factor variable. This can be useful for ensuring that matched groups come from qualitatively different groups.
A factor across which matches should be allowed.
A logical or binary vector the same length as
xindicating treatment and control for each unit in the study. TRUE or 1 represents a treatment unit, FALSE of 0 represents a control unit. NA units are excluded.
exactMatch function provides a way of specifying
a matching problem where only units within a factor level may be
matched. This function provides the reverse scenario: a matching
problem in which only units across factor levels are permitted to
exactMatch, the results of this function will
most often be used as a
within argument to
match_on or another distance specification creation
function to limit the scope of the final distance specification
(i.e., disallowing any match between units with the same value on
the factor variable
data(nuclearplants) # force entries to be within the same factor: em <- fullmatch(exactMatch(pr ~ pt, data = nuclearplants), data = nuclearplants) table(nuclearplants$pt, em) #> em #> 0.1 0.2 0.3 0.4 0.5 0.6 0.7 1.1 1.2 1.3 #> 0 2 2 2 2 2 2 14 0 0 0 #> 1 0 0 0 0 0 0 0 2 2 2 # force treated and control units to have different values of `pt`: z <- nuclearplants$pr names(z) <- rownames(nuclearplants) aem <- fullmatch(antiExactMatch(nuclearplants$pt, z), data = nuclearplants) table(nuclearplants$pt, aem) #> aem #> 1.1 1.10 1.2 1.3 1.8 1.9 #> 0 4 16 1 2 2 1 #> 1 1 1 1 1 1 1