Package 'PSpower'

Plot density of propensity scores given treatment probability and overlap coefficient

Description

Plot density of propensity scores given treatment probability and overlap coefficient

Usage

plot_overlap(r, phi)

Arguments

r	treatment probability
phi	overlap coefficient

Value

a ggplot of the density of propensity scores in two treatment arms

Examples

plot_overlap(0.6, 0.9)

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Plots PSpower object

Description

Plots PSpower object

Usage

## S3 method for class 'PSpower'
plot(x, power = seq(0.6, 0.99, length.out = 100), ...)

Arguments

x	PSpower object
power	a range of powers to plot the power curve
...	ignored

Value

an object (class ggplot) containing a figure

Examples

obj <- PSpower(tau = 1/sqrt(20), sig.level = 0.05, power = 0.956,
               r = 0.5, phi = 0.99, rho_sq = 0.02)
plot(obj)

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Prints PSpower object

Description

Prints PSpower object

Usage

## S3 method for class 'PSpower'
print(x, ...)

Arguments

x	PSpower object
...	ignored

Value

no return value; called for side effect to output a string

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Calculate sample size needed to achieve a prespecified power

Description

Calculate sample size needed to achieve a prespecified power

Usage

PSpower(
  tau,
  sig.level = 0.05,
  power = NULL,
  sample.size = NULL,
  r,
  phi,
  rho_sq,
  test = "two-sided",
  estimand = "ATE"
)

Arguments

tau	the anticipated standardized treatment effect
sig.level	the significance level, or the type-I error rate (default 0.05)
power	the desired power to achieve (only specify for sample size calculation)
sample.size	the total sample size (only specify for power calculation)
r	the proportion of treated units
phi	the overlap coefficient (usually between 0.8 and 1); use function plot_overlap(r, phi) for visual aid
rho_sq	the squared correlation between propensity score and outcome; recommend treating as a sensitivity parameter: a grid of values between 0 and the R-squared statistic of predicting the outcomes with covariates.
test	whether one-sided or two-sided test is considered
estimand	the estimand (ATE, ATT, ATC or ATO), or a customized tilting function h(e(x))

Value

an object with the calculated sample size

Examples

PSpower(tau = 1/sqrt(20), sig.level = 0.05, power = 0.956, r = 0.5, phi = 0.99, rho_sq = 0.02)

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