matchOnPs uses the provided propensity scores to match target to comparator persons.
matchOnPs( population, caliper = 0.2, caliperScale = "standardized logit", maxRatio = 1, stratificationColumns = c() )
A data frame with the three columns described below.
The caliper for matching. A caliper is the distance which is acceptable for any match. Observations which are outside of the caliper are dropped. A caliper of 0 means no caliper is used.
The scale on which the caliper is defined. Three scales are supported:
The maximum number of persons int the comparator arm to be matched to each person in the treatment arm. A maxRatio of 0 means no maximum: all comparators will be assigned to a target person.
Names or numbers of one or more columns in the
Returns a date frame with the same columns as the input data plus one extra column: stratumId. Any rows that could not be matched are removed
The data frame should have at least the following three columns:
|(numeric)||A unique identifier for each row (e.g. the person ID)|
|(integer)||Column indicating whether the person is in the target (1) or comparator|
This function implements the greedy variable-ratio matching algorithm described in Rassen et al (2012).
The default caliper (0.2 on the standardized logit scale) is the one recommended by Austin (2011).
Rassen JA, Shelat AA, Myers J, Glynn RJ, Rothman KJ, Schneeweiss S. (2012) One-to-many propensity score matching in cohort studies, Pharmacoepidemiology and Drug Safety, May, 21 Suppl 2:69-80.
Austin, PC. (2011) Optimal caliper widths for propensity-score matching when estimating differences in means and differences in proportions in observational studies, Pharmaceutical statistics, March, 10(2):150-161.
rowId <- 1:5 treatment <- c(1, 0, 1, 0, 1) propensityScore <- c(0, 0.1, 0.3, 0.4, 1) age_group <- c(1, 1, 1, 1, 1) data <- data.frame(rowId = rowId, treatment = treatment, propensityScore = propensityScore, age_group = age_group) result <- matchOnPs(data, caliper = 0, maxRatio = 1, stratificationColumns = "age_group")