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Compute covariate balance before and after PS adjustment

Source: R/Balance.R
computeCovariateBalance.Rd

For every covariate, prevalence in treatment and comparator groups before and after matching/trimming/weighting are computed. When variable ratio matching was used the balance score will be corrected according the method described in Austin et al (2008).

Usage

computeCovariateBalance(
  population,
  cohortMethodData,
  computeCovariateBalanceArgs = createComputeCovariateBalanceArgs()
)

Arguments

population

A data frame containing the people that are remaining after PS adjustment.

cohortMethodData

An object of type CohortMethodData as generated using getDbCohortMethodData().

computeCovariateBalanceArgs

Settings object as created by createComputeCovariateBalanceArgs().

Value

Returns a tibble describing the covariate balance before and after PS adjustment, with one row per covariate, with the same data as the covariateRef table in the CohortMethodData object, and the following additional columns:

  • beforeMatchingMeanTarget: The (weighted) mean value in the target before PS adjustment.

  • beforeMatchingMeanComparator: The (weighted) mean value in the comparator before PS adjustment.

  • beforeMatchingSumTarget: The (weighted) sum value in the target before PS adjustment.

  • beforeMatchingSumComparator: The (weighted) sum value in the comparator before PS adjustment.

  • beforeMatchingSdTarget: The standard deviation of the value in the target before PS adjustment.

  • beforeMatchingSdComparator: The standard deviation of the value in the comparator before PS adjustment.

  • beforeMatchingMean: The mean of the value across target and comparator before PS adjustment.

  • beforeMatchingSd: The standard deviation of the value across target and comparator before PS adjustment.

  • beforeMatchingStdDiff: The standardized difference of means when comparing the target to the comparator before PS adjustment.

  • beforeMatchingSdmVariance: The variance of the standardized difference of the means when comparing the target to the comparator before PS adjustment.

  • beforeMatchingSdmP : The P-value for whether abs(beforeMatchingStdDiff) exceeds the threshold.

  • beforeMatchingBalanced : TRUE if the covariate is considered balanced between the target and comparator before PS adjustment (depending on the threshold and alpha settings).

  • afterMatchingMeanTarget: The (weighted) mean value in the target after PS adjustment.

  • afterMatchingMeanComparator: The (weighted) mean value in the comparator after PS adjustment.

  • afterMatchingSumTarget: The (weighted) sum value in the target after PS adjustment.

  • afterMatchingSumComparator: The (weighted) sum value in the comparator after PS adjustment.

  • afterMatchingSdTarget: The standard deviation of the value in the target after PS adjustment.

  • afterMatchingSdComparator: The standard deviation of the value in the comparator after PS adjustment.

  • afterMatchingMean: The mean of the value across target and comparator after PS adjustment.

  • afterMatchingSd: The standard deviation of the value across target and comparator after PS adjustment.

  • afterMatchingStdDiff: The standardized difference of means when comparing the target to the comparator after PS adjustment.

  • afterMatchingSdmVariance: The variance of the standardized difference of the means when comparing the target to the comparator after PS adjustment.

  • afteMatchingSdmP : The P-value for whether abs(beforeMatchingStdDiff) exceeds the threshold.

  • afteMatchingBalanced : TRUE if the covariate is considered balanced between the target and comparator before PS adjustment (depending on the threshold and alpha settings).

  • targetStdDiff: The standardized difference of means when comparing the target before PS adjustment to the target after PS adjustment.

  • comparatorStdDiff: The standardized difference of means when comparing the comparator before PS adjustment to the comparator after PS adjustment. -targetComparatorStdDiff: The standardized difference of means when comparing the entire population before PS adjustment to the entire population after PS adjustment.

The 'beforeMatchingStdDiff' and 'afterMatchingStdDiff' columns inform on the balance: are the target and comparator sufficiently similar in terms of baseline covariates to allow for valid causal estimation?

The 'targetStdDiff', 'comparatorStdDiff', and 'targetComparatorStdDiff' columns inform on the generalizability: are the cohorts after PS adjustment sufficiently similar to the cohorts before adjustment to allow generalizing the findings to the original cohorts?

Details

The population data frame should have the following three columns:

  • rowId (numeric): A unique identifier for each row (e.g. the person ID).

  • treatment (integer): Column indicating whether the person is in the target (1) or comparator (0) group.

  • propensityScore (numeric): Propensity score.

References

Austin, PC (2008) Assessing balance in measured baseline covariates when using many-to-one matching on the propensity-score. Pharmacoepidemiology and Drug Safety, 17: 1218-1225.

Hripcsak G, Zhang L, Chen Y, Li K, Suchard MA, Ryan PB, Schuemie MJ (2025) Assessing Covariate Balance with Small Sample Sizes. Stat Med. 2025 Aug;44(18-19):e70212.