RRor: RR estimate from logistic regression.

In ABS-dev/PF: Prevented fraction

RR estimate from logistic regression.

Description

Model based interval estimate of the risk ratio or prevented fraction from a logistic regression model.

Usage

RRor(
  fit = NULL,
  beta.hat = NULL,
  var.beta.hat = NULL,
  degf = NULL,
  which = c(1, 2),
  pf = TRUE,
  norm = FALSE,
  alpha = 0.05,
  rnd = 3
)

Arguments

fit	A glm object.
beta.hat	Parameters estimates from a logistic regression with no intercept.
var.beta.hat	Variance-covariance matrix from a logistic regression with no intercept.
degf	Degrees of freedom.
which	Numeric vector indicating which parameters to compare, so that RR = compare[2]/compare[1]
pf	Estimate RR or its complement PF?
norm	Estimate confidence interval using quantiles of Guassian rather than t distribution quantiles?
alpha	Complement of the confidence level.
rnd	Number of digits for rounding. Affects display only, not estimates.

Details

Estimates confidence intervals using the delta method on parameters from a generalized linear model with logit link.

RR={{{\mu}}_{2}}/{{{\mu}}_{1}}, where {\mu}_{i} are the estimated probabilities from the model.

Value

A rror object with the following fields.

estimate	vector with point and interval estimate
estimator	either PF or RR
mu	matrix with rows giving probability estimates for each of the groups
rnd	how many digits to round the display
alpha	complement of confidence level
norm	logical indicating Gaussian or t interval
degf	degrees of freedom

Note

Call to this function may be one of two formats: (1) specify fit or (2) beta.hat, var.beta.hat, degf RRor(fit, degf = NULL, pf = TRUE, alpha = 0.05, which = c(1, 2), norm = TRUE, rnd = 3)

RRor(beta.hat, var.beta.hat, degf, pf = TRUE, alpha = 0.05, which = c(1, 2), norm = TRUE, rnd = 3)

Author(s)

PF-package

See Also

rror, phiWt, tauWt StatWI007 for more examples

Examples

bird.fit <- glm(cbind(y, n - y) ~ tx - 1, binomial, bird)
RRor(tauWt(bird.fit))

# 95% t intervals on 4 df
#
# PF
#     PF     LL     UL
#  0.500 -0.583  0.842
#
#       mu.hat    LL     UL
# txcon  0.733 0.943 0.3121
# txvac  0.367 0.752 0.0997

RRor(phiWt(bird.fit))
# 95% t intervals on 4 df
#
# PF
#     PF     LL     UL
#  0.500 -0.583  0.842
#
#       mu.hat    LL     UL
# txcon  0.733 0.943 0.3121
# txvac  0.367 0.752 0.0997

ABS-dev/PF documentation built on April 26, 2024, 3:29 p.m.