MarginalProbs: Computes marginal probabilities for a dataset where the...

In Surrogate: Evaluation of Surrogate Endpoints in Clinical Trials

Computes marginal probabilities for a dataset where the surrogate and true endpoints are binary

Description

This function computes the marginal probabilities associated with the distribution of the potential outcomes for the true and surrogate endpoint.

Usage

MarginalProbs(Dataset=Dataset, Surr=Surr, True=True, Treat=Treat)

Arguments

Dataset	A data.frame that should consist of one line per patient. Each line contains (at least) a binary surrogate value, a binary true endpoint value, and a treatment indicator.
Surr	The name of the variable in Dataset that contains the binary surrogate endpoint values. Should be coded as 0 and 1.
True	The name of the variable in Dataset that contains the binary true endpoint values. Should be coded as 0 and 1.
Treat	The name of the variable in Dataset that contains the treatment indicators. The treatment indicator should be coded as 1 for the experimental group and -1 for the control group.

Value

Theta_T0S0	The odds ratio for S and T in the control group.
Theta_T1S1	The odds ratio for S and T in the experimental group.
Freq.Cont	The frequencies for S and T in the control group.
Freq.Exp	The frequencies for S and T in the experimental group.
pi1_1_	The estimated \pi_{1 \cdot 1 \cdot}
pi0_1_	The estimated \pi_{0 \cdot 1 \cdot}
pi1_0_	The estimated \pi_{1 \cdot 0 \cdot}
pi0_0_	The estimated \pi_{0 \cdot 0 \cdot}
pi_1_1	The estimated \pi_{\cdot 1 \cdot 1}
pi_1_0	The estimated \pi_{\cdot 1 \cdot 0}
pi_0_1	The estimated \pi_{\cdot 0 \cdot 1}
pi_0_0	The estimated \pi_{\cdot 0 \cdot 0}

Author(s)

Wim Van der Elst, Ariel Alonso, & Geert Molenberghs

See Also

ICA.BinBin

Examples

# Open the ARMD dataset and recode Diff24 and Diff52 as 1
# when the original value is above 0, and 0 otherwise
data(ARMD)
ARMD$Diff24_Dich <- ifelse(ARMD$Diff24>0, 1, 0)
ARMD$Diff52_Dich <- ifelse(ARMD$Diff52>0, 1, 0)

# Obtain marginal probabilities and ORs
MarginalProbs(Dataset=ARMD, Surr=Diff24_Dich, True=Diff52_Dich, 
Treat=Treat)

Surrogate documentation built on June 22, 2024, 9:16 a.m.