# Calculate covariate effect size differences before and after stratification.

### Description

This function is modified from the `cv.bal.psa`

function in the
`PSAgrpahics`

package.

### Usage

1 2 3 4 |

### Arguments

`covariates` |
dataframe of interest |

`treatment` |
binary vector of 0s and 1s (necessarily? what if character, or 1, 2?) |

`propensity` |
PS scores from some method or other. |

`strata` |
either a vector of strata number for each row of covariate, or one number n in which case it is attempted to group rows by ps scores into n strata of size approximately 1/n. This does not seem to work well in the case of few specific propensity values, as from a tree. |

`int` |
either a number m used to divide [0,1] into m equal length subintervals, or a vector of cut points between 0 an 1 defining the subintervals (perhaps as suggested by loess.psa). In either case these subintervals define strata, so strata can be of any size. |

`tree` |
logical, if unique ps scores are few, as from a recursively partitioned tree, then TRUE will force each ps value to define a stratum. |

`minsize` |
smallest allowable stratum-treatment size. If violated, strata is removed. |

`universal.psd` |
If 'TRUE', forces standard deviations used to be unadjusted for stratification. |

`trM` |
trimming proportion for mean calculations. |

`absolute.es` |
logical, if 'TRUE' routine uses absolute values of all effect sizes. |

`trt.value` |
allows user to specify which value is active treatment, if desired. |

`use.trt.var` |
logical, if true then Rubin-Stuart method using only treatment variance with be used in effect size calculations. |

`verbose` |
logical, controls output that is visibly returned. |

`xlim` |
limits for the x-axis. |

`plot.strata` |
logical indicating whether to print strata. |

`na.rm` |
should missing values be removed. |

`...` |
currently unused. |

### Details

Note: effect sizes are calculated as treatment 1 - treatment 0, or treatment B - treatment A.

### Author(s)

Robert M. Pruzek RMPruzek@yahoo.com

James E. Helmreich James.Helmreich@Marist.edu

KuangNan Xiong harryxkn@yahoo.com

Jason Bryer jason@bryer.org