presolve_EMD

Determine how many controls should be chosen from each stratum to minimize
the distance between the strata of the chosen controls and those that were desired.
Used within <code>generate_qs()</code>.

internal

Natural strata can be used in observational studies to balance
the distributions of many covariates across any number of treatment
groups and any number of comparisons. These strata have proportional
amounts of units within each stratum across the treatments, allowing
for simple interpretation and aggregation across strata. Within each
stratum, the units are chosen using randomized rounding of a linear
program that balances many covariates. For more details, see Brumberg et al. (2022) <doi:10.1111/rssa.12848> and Brumberg et al.(2023) <doi:10.1093/jrsssc/qlad010>.
To solve the linear program, the 'Gurobi' commercial optimization software
is recommended, but not required. The 'gurobi' R package can be installed by following the instructions at <https://docs.gurobi.com/projects/optimizer/en/current/reference/r/setup.html> after claiming your free academic license at <https://www.gurobi.com/academia/academic-program-and-licenses/>.

Katherine Brumberg

natstrat

Obtain Unweighted Natural Strata that Balance Many Covariates

presolve_EMD function

<dl><dt>S</dt>
<dd>the total number of strata.</dd>
<dt>desired_qs</dt>
<dd>a named vector containing the number of controls desired in
each stratum with names matching the strata names.</dd>
<dt>max_s</dt>
<dd>a vector containing the maximum number of controls that should
be selected in each stratum. The order of the strata should match that of <code>desired_qs</code>.</dd>
<dt>strata_dist_flat</dt>
<dd>a flattened distance matrix between the strata.</dd></dl>

Arguments

Solve the earthmover's distance problem — presolve_EMD

<dl>

<dt>S</dt>
<dd>the total number of strata.</dd>


<dt>desired_qs</dt>
<dd>a named vector containing the number of controls desired in
each stratum with names matching the strata names.</dd>


<dt>max_s</dt>
<dd>a vector containing the maximum number of controls that should
be selected in each stratum. The order of the strata should match that of <code>desired_qs</code>.</dd>


<dt>strata_dist_flat</dt>
<dd>a flattened distance matrix between the strata.</dd>

</dl>

presolve_EMD: Solve the earthmover's distance problem

Description

Usage

Value

Arguments