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

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### Description

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

### Usage

 1 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 π_{1 \cdot 1 \cdot} pi0_1_ The estimated π_{0 \cdot 1 \cdot} pi1_0_ The estimated π_{1 \cdot 0 \cdot} pi0_0_ The estimated π_{0 \cdot 0 \cdot} pi_1_1 The estimated π_{\cdot 1 \cdot 1} pi_1_0 The estimated π_{\cdot 1 \cdot 0} pi_0_1 The estimated π_{\cdot 0 \cdot 1} pi_0_0 The estimated π_{\cdot 0 \cdot 0}

### Author(s)

Wim Van der Elst, Ariel Alonso, & Geert Molenberghs

ICA.BinBin
 1 2 3 4 5 6 7 8 9 # 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)