Supports Multiple Methods for Defining and Visualizing (PS) Strata

Given propensity scores, allows strata to be directly user defined, possibly to: equalize sizes of strata, equalize the ranges of propensity scores, or to specify cut points on the unit interval. Once strata are created, a simple graphic is generated to visualize or judge strata for overlap and appropriateness. If a regression tree has been used, propensity scores are defined for each leaf of the tree.

cstrata.psa(
  treatment,
  propensity,
  strata = NULL,
  int = NULL,
  tree = FALSE,
  minsize = 2,
  graphic = TRUE,
  colors = c("dark blue", "dark green"),
  xlab = "Estimated Propensity Scores with Random Heights",
  pch = c(16, 16)
)

Arguments

treatment: Binary vector or factor defining the two treatments
propensity: Vector of same length as treatment containing estimated propensity scores.
strata: Either a vector of same length as treatment of predefined stratum number, or one integer n used to assign rows to n strata propensity scores, each of approximately the same number of cases. If relatively few unique propensity scores have been defined (as from a classification tree) then the logical tree should be set equal to TRUE.
int: Either a number m used to divide [0,1] into m equal length subintervals, or a vector containing cut points between 0 and 1 that define subintervals (perhaps as suggested by loess.psa). In either case the subintervals define strata, for which sizes can differ.
tree: Logical, default FALSE. If there are few unique propensity scores, say from a recursively partitioned tree, then TRUE forces strata to be defined by the unique propensity scores.
minsize: Smallest allowable stratum-treatment size. If violated, rows in the stratum are removed. User may wish to redefine strata.
graphic: Logical, default TRUE. If set to FALSE the graphic is not provided.
colors: 2-ary color vector. Sets the colors of the points in the graphic. Default = c("blue", "orange")
xlab: Label for the x axis; default = "Estimated Propensity Scores with Random Heights".
pch: 2-ary vector; determines the shape of points in the graphic. Default = c(16, 16).

Value

Original.Strata: Table of strata-treatment sizes before minsize evaluation.
Used.Strata: Table of strata-treatment sizes after minsize evaluation.
strata: Vector of the same length as treatment, indicating either the strata input by user or those created by the function.

Author

James E. Helmreich James.Helmreich@Marist.edu

Robert M. Pruzek RMPruzek@yahoo.com

KuangNan Xiong harryxkn@yahoo.com

Examples


data(lindner)
attach(lindner)
#> The following objects are masked from lindner (pos = 3):
#> 
#>     abcix, acutemi, cardbill, diabetic, ejecfrac, female, height,
#>     lifepres, stent, ves1proc
#> The following objects are masked from lindner (pos = 4):
#> 
#>     abcix, acutemi, cardbill, diabetic, ejecfrac, female, height,
#>     lifepres, stent, ves1proc
#> The following objects are masked from lindner (pos = 5):
#> 
#>     abcix, acutemi, cardbill, diabetic, ejecfrac, female, height,
#>     lifepres, stent, ves1proc
lindner.ps <- glm(abcix ~ stent + height + female +
      diabetic + acutemi + ejecfrac + ves1proc,
      data = lindner, family = binomial)
ps <- lindner.ps$fitted
cstrata.psa(abcix, ps, strata = 5)

#> $Original.Strata
#>     1   2   3   4   5
#> 0  94  76  64  44  20
#> 1 105 123 134 156 180
#> 
#> $Used.Strata
#>               1   2   3   4   5
#> 0            94  76  64  44  20
#> 1           105 123 134 156 180
#> Strata.Size 199 199 198 200 200
#> 
#> $strata
#>   [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1
#>  [38] 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
#>  [75] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 1 2 2 2
#> [112] 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
#> [149] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
#> [186] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
#> [223] 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [260] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4
#> [297] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [334] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 3 3 3 3 3 3 4 3 3 3 3 3 4 3 3 3 3 3 4 4 4 4
#> [371] 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
#> [408] 4 4 4 4 4 4 4 4 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 4 4 4 4 4 4 4 4 4 4 4
#> [445] 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
#> [482] 4 4 4 4 4 4 4 4 4 5 4 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
#> [519] 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 4
#> [556] 5 5 5 5 5 5 5 5 5 4 5 5 5 5 5 5 5 5 5 5 5 5 5 4 5 5 5 5 5 5 5 5 5 5 5 5 5
#> [593] 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
#> [630] 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
#> [667] 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 1 1 1 1 1
#> [704] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
#> [741] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
#> [778] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
#> [815] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
#> [852] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 2 3 3 3 3 3 3 3 3
#> [889] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [926] 3 3 3 3 3 4 4 4 3 4 4 4 4 4 4 4 3 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
#> [963] 4 4 4 4 4 4 4 4 4 4 4 4 4 4 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
#> 
cstrata.psa(abcix, ps, strata = 10)

#> $Original.Strata
#>    1  2  3  4  5  6  7  8  9 10
#> 0 58 36 36 40 29 35 25 19 11  9
#> 1 42 63 64 59 71 63 76 80 89 91
#> 
#> $Used.Strata
#>               1  2   3  4   5  6   7  8   9  10
#> 0            58 36  36 40  29 35  25 19  11   9
#> 1            42 63  64 59  71 63  76 80  89  91
#> Strata.Size 100 99 100 99 100 98 101 99 100 100
#> 
#> $strata
#>   [1]  1  2  1  1  1  2  1  2  2  1  2  2  1  1  2  2  2  2  1  1  1  1  2  2  1
#>  [26]  2  2  1  2  1  2  2  2  1  3  1  2  1  3  2  1  1  1  1  2  1  2  2  2  1
#>  [51]  2  1  2  1  2  2  1  2  1  1  1  2  2  2  2  1  2  2  1  1  2  1  2  2  2
#>  [76]  2  2  2  1  1  2  1  2  2  2  2  2  2  1  2  2  2  1  2  2  2  2  1  2  1
#> [101]  2  1  2  2  2  3  3  2  4  3  4  3  3  4  4  4  3  4  2  3  3  4  4  3  3
#> [126]  3  3  3  3  4  4  4  4  4  3  4  3  3  3  3  4  4  3  3  3  4  4  3  4  4
#> [151]  3  4  3  4  3  4  4  4  4  4  3  3  4  4  3  4  3  3  3  4  4  4  4  4  4
#> [176]  3  4  3  3  4  3  4  4  3  3  4  3  4  3  4  3  3  4  3  4  3  3  3  4  4
#> [201]  4  3  4  3  3  5  3  4  3  4  3  3  3  4  3  4  4  3  4  4  3  3  3  3  3
#> [226]  4  3  4  4  5  5  5  5  5  5  6  6  6  5  6  5  5  6  5  5  5  5  6  5  5
#> [251]  6  5  6  6  5  5  5  5  6  5  5  5  6  6  6  6  5  5  6  6  6  6  6  5  6
#> [276]  5  5  6  6  5  6  6  5  6  5  5  5  5  6  6  5  5  6  6  5  7  6  5  5  5
#> [301]  6  5  5  6  5  5  6  6  5  6  5  6  6  5  5  6  6  5  5  5  6  5  5  5  6
#> [326]  5  5  6  6  5  5  6  6  5  5  6  6  5  6  6  6  5  6  6  6  6  6  7  6  6
#> [351]  6  5  5  6  7  5  6  5  5  6  7  5  5  6  5  6  7  7  7  8  8  7  7  8  7
#> [376]  8  7  7  7  7  8  8  8  8  8  8  7  7  7  7  8  7  8  7  7  7  8  8  8  7
#> [401]  8  7  8  8  8  7  7  7  8  8  7  8  7  8  7  9  7  8  7  7  8  7  8  8  7
#> [426]  7  7  7  8  7  7  7  9  8  7  7  7  7  8  8  7  8  7  8  8  8  8  8  7  7
#> [451]  8  8  8  7  7  7  8  8  7  7  7  7  8  8  8  7  8  8  8  8  8  8  7  7  8
#> [476]  7  8  8  7  8  8  8  8  8  8  7  7  8  8  8  9  7  9  8  8  7  8  7  7  8
#> [501]  7  7  7  8  8  8  7  8  8  8  8  7  7  8  8  8  7  7  7 10  9  9  9 10 10
#> [526]  9  9  9  9 10 10 10 10 10  9  9 10 10  9  9  9  9  9  9 10  9  9  9 10  9
#> [551] 10 10  9  9  8 10 10  9  9 10  9  9 10  9  8  9 10 10  9  9  9  9  9  9  9
#> [576]  9  9 10  8 10  9 10 10 10 10  9  9 10 10 10 10  9 10 10 10  9 10 10 10  9
#> [601]  9 10  9 10  9  9 10  9  9  9  9  9 10 10  9 10 10  9  9 10 10  9 10  9  9
#> [626]  9  9 10  9 10 10 10 10 10 10 10 10 10 10  9  9  9 10 10  9 10 10 10 10  9
#> [651] 10  9 10  9 10  9  9 10 10  9 10 10  9  9 10  9 10 10 10  9  9 10 10  9 10
#> [676]  9 10  9 10 10 10 10 10  9  9 10 10  9  9 10  9 10 10 10  9  9 10 10  1  1
#> [701]  2  1  1  1  1  2  1  2  1  1  1  1  2  1  1  1  1  2  1  1  2  1  1  1  1
#> [726]  2  2  1  1  1  2  1  2  2  2  1  2  1  1  1  1  2  2  1  1  2  1  1  2  1
#> [751]  2  1  2  1  1  2  2  2  2  2  2  2  1  1  1  2  1  1  1  1  1  1  1  1  2
#> [776]  2  2  2  2  1  1  2  1  1  1  2  1  1  1  2  2  1  4  3  3  3  4  4  3  3
#> [801]  4  3  3  4  3  3  3  4  4  3  4  4  4  4  4  4  3  4  4  3  4  4  4  4  3
#> [826]  4  4  4  3  4  3  4  3  4  3  4  4  3  4  3  4  3  4  4  3  3  3  3  3  4
#> [851]  4  3  3  4  3  3  4  4  4  3  4  3  3  4  3  3  3  6  6  6  6  6  5  6  6
#> [876]  5  6  5  6  4  5  6  5  6  5  6  6  5  6  5  5  5  6  6  6  5  5  6  5  5
#> [901]  6  5  6  5  5  5  6  6  6  6  5  5  6  6  5  5  5  5  6  6  5  6  6  5  5
#> [926]  6  5  6  6  5  8  8  7  6  8  8  8  7  7  8  7  6  7  7  7  8  7  7  8  8
#> [951]  8  7  7  8  7  8  8  7  7  8  7  8  7  8  7  8  7  7  7  7  7  8  7  7  8
#> [976]  7  9 10 10 10  9  9  9 10  9  9  9 10  9 10 10  9 10  9 10  9
#> 
cstrata.psa(abcix, ps, int = c(.37, .56, .87, 1))

#> $Original.Strata
#>   1  2   3   4
#> 0 2 78 206  12
#> 1 1 77 507 113
#> 
#> $Used.Strata
#>               2   3   4
#> 0            78 206  12
#> 1            77 507 113
#> Strata.Size 155 713 125
#> 
#> $strata
#>   [1] 2 3 2 2 2 3 2 3 2 2 2 3 2 2 2 3 2 2 2 2 2 1 3 3 2 2 2 2 2 2 3 2 2 2 3 2 2
#>  [38] 2 3 2 2 2 2 2 2 2 2 2 3 2 2 2 3 2 2 2 2 2 2 2 2 2 2 3 2 2 3 3 2 2 3 2 2 2
#>  [75] 2 3 2 3 2 2 2 2 3 2 3 2 3 3 2 2 3 3 2 2 2 2 3 2 2 2 2 2 3 3 2 3 3 3 3 3 3
#> [112] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [149] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [186] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [223] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [260] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [297] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [334] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [371] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [408] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [445] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [482] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [519] 3 4 4 3 3 4 4 3 3 3 3 4 4 4 4 4 3 3 4 4 3 4 3 3 3 4 4 4 4 3 4 3 4 4 3 3 3
#> [556] 4 4 4 3 4 4 4 4 3 3 3 4 4 4 3 4 3 3 3 3 3 3 4 3 4 3 4 4 4 4 3 3 4 4 4 4 3
#> [593] 4 4 4 3 4 4 4 3 4 4 4 4 4 3 4 4 3 3 3 3 4 4 4 4 4 3 3 4 4 3 4 3 4 3 4 4 3
#> [630] 4 4 4 4 4 4 4 4 4 4 4 4 3 4 4 3 4 4 4 4 3 4 3 4 4 4 3 3 4 4 3 4 4 4 3 4 3
#> [667] 4 4 4 3 3 4 4 3 4 3 4 3 4 4 4 4 4 3 4 4 4 3 3 4 3 4 4 4 3 3 4 4 2 2 3 2 2
#> [704] 2 2 2 2 3 2 2 2 2 3 2 2 1 2 2 2 2 3 2 2 2 2 2 2 2 2 2 3 2 3 2 3 2 2 2 2 2
#> [741] 2 3 2 2 2 2 2 1 2 2 2 2 3 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 2
#> [778] 2 3 2 2 2 2 2 2 3 2 2 2 2 3 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [815] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [852] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [889] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [926] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
#> [963] 3 3 3 3 3 3 3 3 3 3 3 3 3 3 4 4 4 4 3 4 3 4 3 3 3 4 3 4 4 3 4 4 4 3
#>

Supports Multiple Methods for Defining and Visualizing (PS) Strata

Arguments

Value

See also

Author

Examples