Create a weightit object manually

This function allows users to get the benefits of a weightit object when using weights not estimated with weightit() or weightitMSM(). These benefits include diagnostics, plots, and direct compatibility with cobalt for assessing balance.

Usage

as.weightit(x, ...)

# S3 method for class 'weightit.fit'
as.weightit(x, covs = NULL, ...)

# Default S3 method
as.weightit(
  x,
  treat,
  covs = NULL,
  estimand = NULL,
  s.weights = NULL,
  ps = NULL,
  ...
)

as.weightitMSM(x, ...)

# Default S3 method
as.weightitMSM(
  x,
  treat.list,
  covs.list = NULL,
  estimand = NULL,
  s.weights = NULL,
  ps.list = NULL,
  ...
)

Arguments

x

required; a numeric vector of weights, one for each unit, or a weightit.fit object from weightit.fit().

...

additional arguments. These must be named. They will be included in the output object.

covs

an optional data frame of covariates. For using WeightIt functions, this is not necessary, but for use with cobalt it is. Note that when using with a weightit.fit object, this should not be the matrix supplied to the covs argument of weightit.fit() unless there are no factor/character variables in it. Ideally this is the original, unprocessed covariate data frame with factor variables included.

treat

a vector of treatment statuses, one for each unit. Required when x is a vector of weights.

estimand

an optional character of length 1 giving the estimand. The text is not checked.

s.weights

an optional numeric vector of sampling weights, one for each unit.

ps

an optional numeric vector of propensity scores, one for each unit.

treat.list

a list of treatment statuses at each time point.

covs.list

an optional list of data frames of covariates at each time point. For using WeightIt functions, this is not necessary, but for use with cobalt it is.

ps.list

an optional list of numeric vectors of propensity scores at each time point.

Value

An object of class weightit (for as.weightit()) or weightitMSM (for as.weightitMSM()).

Examples

treat <- rbinom(500, 1, .3)
weights <- rchisq(500, df = 2)

W <- as.weightit(weights, treat = treat, estimand = "ATE")
summary(W)
#>                   Summary of weights
#> 
#> ─ Weight ranges:
#> 
#>           Min                                  Max
#> Treated 0.019 ╞═══════════════════╡          8.843
#> Control 0.004 ╞═══════════════════════════╡ 12.028
#> 
#> ─ Units with the 5 most extreme weights by group:
#>                                         
#>             88   271    60    403     99
#>  Treated  6.23 7.314 7.614   7.65  8.843
#>            169   187   430     50    415
#>  Control 8.826  8.83 9.904 11.167 12.028
#> 
#> ─ Weight statistics:
#> 
#>         Coef of Var   MAD Entropy # Zeros
#> Treated       0.947 0.766   0.411       0
#> Control       1.002 0.734   0.43        0
#> 
#> ─ Effective Sample Sizes:
#> 
#>            Control Treated
#> Unweighted  346.    154.  
#> Weighted    172.99   81.44

# See ?weightit.fit for using as.weightit() with a
# weightit.fit object.