Package 'emplik2'

Title: Empirical Likelihood Ratio Test for Two-Sample U-Statistics with Censored Data
Description: Calculates the empirical likelihood ratio and p-value for a mean-type hypothesis (or multiple mean-type hypotheses) based on two samples with possible censored data.
Authors: William H. Barton [aut], Mai Zhou [cre, aut]
Maintainer: Mai Zhou <[email protected]>
License: GPL (>= 2)
Version: 1.33
Built: 2025-02-18 03:39:48 UTC
Source: https://github.com/cran/emplik2

Help Index


Computes empirical likelihood ratio and p-value for multiple mean-type hypotheses, based on two independent samples that may contain censored data.

Description

This function is similar to el2.cen.EMs but for several mean type restrictions. This function uses the EM algorithm to calculate a maximized empirical likelihood ratio for a set of pp simultaneous hypotheses as follows:

Ho:E(g(x,y)mean)=0H_o: E(g(x,y)-mean)=0

where EE indicates expected value; g(x,y)g(x,y) is a vector of user-defined functions: g1(x,y),,gp(x,y)g_1(x,y), \ldots, g_p(x,y); and meanmean is a vector of pp hypothesized values of E(g(x,y))E(g(x,y)). The two samples xx and yy are assumed independent. They may be uncensored, right-censored, left-censored, or left-and-right (“doubly”) censored. A p-value for HoH_o is also calculated, based on the assumption that -2*log(empirical likelihood ratio) is asymptotically distributed as chisq(df=p).

Usage

el2.cen.EMm(x, dx, wx=rep(1,length(x)), y, dy, wy=rep(1,length(y)), 
            p, H, xc=1:length(x), yc=1:length(y), mean, maxit=35)

Arguments

x

a vector of the data for the first sample

dx

a vector of the censoring indicators for x: 0=right-censored, 1=uncensored, 2=left-censored

wx

a vector of data case weight for x

y

a vector of the data for the second sample

dy

a vector of the censoring indicators for y: 0=right-censored, 1=uncensored, 2=left-censored

wy

a vector of data case weight for y

p

the number of hypotheses

H

a matrix defined as H=[H1,H2,,Hp]H = [H_1, H_2, \ldots, H_p], where Hk=[gk(xi,yj)muk],k=1,,pH_k = [g_k(x_i,y_j)-mu_k], k=1, \ldots, p

xc

a vector containing the indices of the x datapoints, controls if tied x collapse or not

yc

a vector containing the indices of the y datapoints, ditto

mean

the hypothesized value of E(g(x,y)E(g(x,y))

maxit

a positive integer used to control the maximum number of iterations of the EM algorithm; default is 35

Details

The value of meankmean_k should be chosen between the maximum and minimum values of gk(xi,yj)g_k(x_i,y_j); otherwise there may be no distributions for xx and yy that will satisfy HoH_o. If meankmean_k is inside this interval, but the convergence is still not satisfactory, then the value of meankmean_k should be moved closer to the NPMLE for E(gk(x,y))E(g_k(x,y)). (The NPMLE itself should always be a feasible value for meankmean_k.)

Value

el2.cen.EMm returns a list of values as follows:

xd1

a vector of unique, uncensored xx-values in ascending order

yd1

a vector of unique, uncensored yy-values in ascending order

temp3

a list of values returned by the el2.test.wtm function (which is called by el2.cen.EMm)

mean

the hypothesized value of E(g(x,y))E(g(x,y))

NPMLE

a non-parametric-maximum-likelihood-estimator vector of E(g(x,y))E(g(x,y))

logel00

the log of the unconstrained empirical likelihood

logel

the log of the constrained empirical likelihood

"-2LLR"

-2*(log-likelihood-ratio) for the p simultaneous hypotheses

Pval

the p-value for the p simultaneous hypotheses, equal to 1 - pchisq(-2LLR, df = p)

logvec

the vector of successive values of logel computed by the EM algorithm (should converge toward a fixed value)

sum_muvec

sum of the probability jumps for the uncensored xx-values, should be 1

sum_nuvec

sum of the probability jumps for the uncensored yy-values, should be 1

Author(s)

William H. Barton <[email protected]>

References

Barton, W. (2010). Comparison of two samples by a nonparametric likelihood-ratio test. PhD dissertation at University of Kentucky.

Chang, M. and Yang, G. (1987). “Strong Consistency of a Nonparametric Estimator of the Survival Function with Doubly Censored Data.” Ann. Stat.,15, pp. 1536-1547.

Dempster, A., Laird, N., and Rubin, D. (1977). “Maximum Likelihood from Incomplete Data via the EM Algorithm.” J. Roy. Statist. Soc., Series B, 39, pp.1-38.

Gomez, G., Julia, O., and Utzet, F. (1992). “Survival Analysis for Left-Censored Data.” In Klein, J. and Goel, P. (ed.), Survival Analysis: State of the Art. Kluwer Academic Publishers, Boston, pp. 269-288.

Li, G. (1995). “Nonparametric Likelihood Ratio Estimation of Probabilities for Truncated Data.” J. Amer. Statist. Assoc., 90, pp. 997-1003.

Owen, A.B. (2001). Empirical Likelihood. Chapman and Hall/CRC, Boca Raton, pp. 223-227.

Turnbull, B. (1976). “The Empirical Distribution Function with Arbitrarily Grouped, Censored and Truncated Data.” J. Roy. Statist. Soc., Series B, 38, pp. 290-295.

Zhou, M. (2005). “Empirical likelihood ratio with arbitrarily censored/truncated data by EM algorithm.” J. Comput. Graph. Stat., 14, pp. 643-656.

Zhou, M. (2009) emplik package on CRAN website. The function el2.cen.EMm here extends el.cen.EM2 inside emplik package from one-sample to two-samples.

Examples

x<-c(10, 80, 209, 273, 279, 324, 391, 415, 566, 85, 852, 881, 895, 954, 1101, 1133,
1337, 1393, 1408, 1444, 1513, 1585, 1669, 1823, 1941)
dx<-c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 1, 1, 0)
y<-c(21, 38, 39, 51, 77, 185, 240, 289, 524, 610, 612, 677, 798, 881, 899, 946, 1010,
1074, 1147, 1154, 1199, 1269, 1329, 1484, 1493, 1559, 1602, 1684, 1900, 1952)
dy<-c(1,1,1,1,1,1,2,2,1,1,1,1,1,2,1,1,1,1,1,1,0,0,1,1,0,0,1,0,0,0)
nx<-length(x)
ny<-length(y)
xc<-1:nx
yc<-1:ny
wx<-rep(1,nx)
wy<-rep(1,ny)
mu=c(0.5,0.5)
p <- 2
H1<-matrix(NA,nrow=nx,ncol=ny)
H2<-matrix(NA,nrow=nx,ncol=ny)
for (i in 1:nx) {
  for (j in 1:ny) {
   H1[i,j]<-(x[i]>y[j])
   H2[i,j]<-(x[i]>1060) } }
H=matrix(c(H1,H2),nrow=nx,ncol=p*ny)

# Ho1: X is stochastically equal to Y (i.e. P(X>Y)=0.5)
# Ho2: P(X>1060)=0.5 

el2.cen.EMm(x=x, dx=dx, y=y, dy=dy, p=2, H=H, mean=mu)

# Result: Pval is 0.6310234, so we cannot with 95 percent confidence reject the two
# simultaneous hypotheses Ho1 and Ho2

Computes empirical likelihood ratio and p-value for a single mean-type hypothesis, based on two independent samples that may contain censored data.

Description

This function uses the EM algorithm to calculate a maximized empirical likelihood ratio for the hypothesis

Ho:E(g(x,y)mean)=0H_o: E(g(x,y)-mean)=0

where EE indicates expected value; g(x,y)g(x,y) is a user-defined function of xx and yy; and meanmean is the hypothesized value of E(g(x,y))E(g(x,y)). The default: g(x,y)=I[xy]g(x,y)=I[x \geq y], mean=0.5mean=0.5. The samples xx and yy are assumed independent. They may be uncensored, right-censored, left-censored, or left-and-right (“doubly”) censored. A p-value for HoH_o is also calculated, based on the assumption that -2*log(empirical likelihood ratio) is approximately distributed as chisq(df=1).

Usage

el2.cen.EMs(x,dx,y,dy,fun=function(x,y){x>=y},mean=0.5,
                                tol.u=1e-6,tol.v=1e-6,maxit=50)

Arguments

x

a vector of the data for the first sample

dx

a vector of the censoring indicators for x: 0=right-censored, 1=uncensored, 2=left-censored

y

a vector of the data for the second sample

dy

a vector of the censoring indicators for y: 0=right-censored, 1=uncensored, 2=left-censored

fun

a user-defined, weight-function g(x,y)g(x,y) used to define the mean in the hypothesis HoH_o. The default is fun=function(x,y){x>=y}.

mean

the hypothesized value of E(g(x,y))E(g(x,y)); default is 0.5

tol.u

Error tolerance for iteration control. L1 norm of the u-uOLD is used. Default 1e-6

tol.v

Error tolerance for iteration control. L1 norm of the v-vOLD is used. Default 1e-6

maxit

a positive integer used to set the maximum number of iterations of the EM algorithm; default is 50

Details

The empirical likelihood used here is

EL(mean)=maxμi,νj{μiνj;s.t.ijg(xi,yj)μiνj=mean;μi=1;νj=1.}EL(mean) = \max_{\mu_i, \nu_j} \left\{ \prod \mu_i \prod \nu_j ; s.t. \sum_i \sum_j g(x_i, y_j) \mu_i \nu_j = mean; \sum \mu_i =1; \sum \nu_j =1. \right\}

for uncensored data. If data were censored, approapriate adjustments are used accordingly. See Owen (2001) section 11.4.

The value of meanmean should be chosen between the maximum and minimum values of g(xi,yj)g(x_i,y_j); otherwise there may be no distributions for xx and yy that will satisfy HoH_o. If meanmean is inside this interval, but the convergence is still not satisfactory, then the value of meanmean should be moved closer to the NPMLE for E(g(x,y))E(g(x,y)). (The NPMLE itself should always be a feasible value for meanmean. This NPMLE value is in the output.)

Value

el2.cen.EMs returns a list of values as follows:

xd1

a vector of the unique, uncensored xx-values in ascending order

yd1

a vector of the unique, uncensored yy-values in ascending order

temp3

a list of values returned by the el2.test.wts function (which is called by el2.cen.EMs)

mean

the hypothesized value of E(g(x,y))E(g(x,y))

funNPMLE

the non-parametric-maximum-likelihood-estimator of E(g(x,y))E(g(x,y))

logel00

the log of the unconstrained empirical likelihood

logel

the log of the constrained empirical likelihood

"-2LLR"

-2*(logel-logel00)

Pval

the estimated p-value for HoH_o, computed as 1-pchisq(-2LLR, df = 1)

logvec

the vector of successive values of logel computed by the EM algorithm (should converge toward a fixed value)

sum_muvec

sum of the probability jumps for the uncensored xx-values, should be 1

sum_nuvec

sum of the probability jumps for the uncensored yy-values, should be 1

constraint

the realized value of i=1nj=1m(g(xi,yj)mean)μiνj\sum_{i=1}^n \sum_{j=1}^m (g(x_i,y_j) - mean) \mu_i \nu_j, where μi\mu_i and νj\nu_j are the probability jumps at xix_i and yjy_j, respectively, that maximize the empirical likelihood ratio. The value of constraint should be close to 0.

Author(s)

William H. Barton <[email protected]> ; modified by Mai Zhou.

References

Barton, W. (2010). Comparison of two samples by a nonparametric likelihood-ratio test. PhD dissertation at University of Kentucky.

Chang, M. and Yang, G. (1987). “Strong Consistency of a Nonparametric Estimator of the Survival Function with Doubly Censored Data.” Ann. Stat.,15, pp. 1536-1547.

Dempster, A., Laird, N., and Rubin, D. (1977). “Maximum Likelihood from Incomplete Data via the EM Algorithm.” J. Roy. Statist. Soc., Series B, 39, pp.1-38.

Gomez, G., Julia, O., and Utzet, F. (1992). “Survival Analysis for Left-Censored Data.” In Klein, J. and Goel, P. (ed.), Survival Analysis: State of the Art. Kluwer Academic Publishers, Boston, pp. 269-288.

Li, G. (1995). “Nonparametric Likelihood Ratio Estimation of Probabilities for Truncated Data.” J. Amer. Statist. Assoc., 90, pp. 997-1003.

Owen, A.B. (2001). Empirical Likelihood. Chapman and Hall/CRC, Boca Raton, pp.223-227.

Turnbull, B. (1976). “The Empirical Distribution Function with Arbitrarily Grouped, Censored and Truncated Data.” J. Roy. Statist. Soc., Series B, 38, pp. 290-295.

Zhou, M. (2005). “Empirical likelihood ratio with arbitrarily censored/truncated data by EM algorithm.” J. Comput. Graph. Stat., 14, pp. 643-656.

Zhou, M. (2009) emplik package on CRAN website. The el2.cen.EMs function here extends the el.cen.EM function inside emplik package from one sample to two-samples.

Examples

x<-c(10,80,209,273,279,324,391,415,566,785,852,881,895,954,1101,
1133,1337,1393,1408,1444,1513,1585,1669,1823,1941)
dx<-c(1,2,1,1,1,1,1,2,1,1,1,1,1,1,1,0,0,1,0,0,0,0,1,1,0)
y<-c(21,38,39,51,77,185,240,289,524,610,612,677,798,881,899,946,
1010,1074,1147,1154,1199,1269,1329,1484,1493,1559,1602,1684,1900,1952)
dy<-c(1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,1,1,1,0,0,0,0,0,0,1,0,0,0)

# Ho1:  X is stochastically equal to Y (i.e. P(X>Y)=0.5) 
el2.cen.EMs(x, dx, y, dy, fun=function(x,y){x>=y}, mean=0.5)
# Result: Pval = 0.7090658, so we cannot with 95 percent confidence reject Ho1
# Remark: may be we should be more careful for the (x=y) cases, if any.

# Ho2: mean of X equals mean of Y
el2.cen.EMs(x, dx, y, dy, fun=function(x,y){x-y}, mean=0)
# Result: Pval = 0.9716493, so we cannot with 95 percent confidence reject Ho2

Computes maximum-likelihood probability jumps for multiple mean-type hypotheses, based on two independent uncensored samples

Description

This function computes the maximum-likelihood probability jumps for multiple mean-type hypotheses, based on two samples that are independent, uncensored, and weighted. The target function for the maximization is the (Lagrangian) constrained log(empirical likelihood) which can be expressed as,

dxi=1wxilogμi+dyj=1wyjlogνjη(1dxi=1μi)δ(1dyj=1νj)λ(μTH1ν,,μTHpν)T\sum_{dx_i=1} wx_i \log{\mu_i} + \sum_{dy_j=1} wy_j \log{\nu_j} - \eta ( 1 -\sum_{dx_i=1} \mu_i ) - \delta ( 1 -\sum_{dy_j=1} \nu_j ) - \lambda ( \mu^T H_1 \nu, \ldots , \mu^T H_p \nu )^T

where the variables are defined as follows:

xx is a vector of uncensored data for the first sample

yy is a vector of uncensored data for the second sample

wxwx is a vector of estimated weights for the first sample

wywy is a vector of estimated weights for the second sample

μ\mu is a vector of estimated probability jumps for the first sample

ν\nu is a vector of estimated probability jumps for the second sample

Hk=[gk(xi,yj)meank],k=1,,pH_k = [ g_k(x_i, y_j) - mean_k ], k=1, \ldots , p, where gk(x,y)g_k(x,y) is a user-chosen function

H=[H1,...,Hp]H = [H_1, ... , H_p] (used as argument in el.cen.EMm function, which calls el2.test.wtm)

meanmean is a vector of length pp of hypothesized means, such that meankmean_k is the hypothesized value of E(gk(x,y))E(g_k(x,y))

EE indicates “expected value”

Usage

el2.test.wtm(xd1,yd1,wxd1new, wyd1new, muvec, nuvec, Hu, Hmu, Hnu, p, mean, maxit=35)

Arguments

xd1

a vector of uncensored data for the first sample

yd1

a vector of uncensored data for the second sample

wxd1new

a vector of estimated weights for xd1

wyd1new

a vector of estimated weights for yd1

muvec

a vector of estimated probability jumps for xd1

nuvec

a vector of estimated probability jumps for yd1

Hu

Hu=[H1[mean1],,Hp[meanp]],dxi=1,dyj=1H_u = [ H_1 - [mean_1], \ldots , H_p - [mean_p] ], dx_i=1, dy_j=1

Hmu

a matrix, whose calculation is shown in the example below

Hnu

a matrix, whose calculation is shown in the example below

p

the number of hypotheses

mean

a vector of hypothesized values of E(gk(u,v)),k=1,,pE(g_k(u,v)), k=1, \ldots,p

maxit

a positive integer used to control the maximum number of iterations in the Newton-Raphson algorithm; default is 35

Details

This function is called by el2.cen.EMm. It is listed here because the user may find it useful elsewhere.

The value of meankmean_k should be chosen between the maximum and minimum values of gk(xd1i,yd1j)g_k(xd1_i,yd1_j); otherwise there may be no distributions for xd1xd1 and yd1yd1 that will satisfy the the mean-type hypothesis. If meankmean_k is inside this interval, but the convergence is still not satisfactory, then the value of meankmean_k should be moved closer to the NPMLE for E(g(xd1,yd1))E(g(xd1,yd1)). (The NPMLE itself should always be a feasible value for meankmean_k.) The calculations for this function are derived in Owen (2001).

Value

el2.test.wtm returns a list of values as follows:

constmat

a matrix of row vectors, where the kkth row vector holds successive values of μTHkν,k=1,,p\mu^T H_k \nu , k=1, \ldots, p, generated by the Newton-Raphson algorith m

lam

the vector of Lagrangian mulipliers used in the calculations

muvec1

the vector of probability jumps for the first sample that maximize the weighted empirical likelihood

nuvec1

the vector of probability jumps for the second sample that maximize the weighted empirical likelihood

mean

the vector of hypothesized means

Author(s)

William H. Barton <[email protected]>

References

Owen, A.B. (2001). Empirical Likelihood. Chapman and Hall/CRC, Boca Raton, pp.223-227.

Examples

#Ho1: P(X>Y) = 0.5
#Ho2: P(X>1060) = 0.5
#g1(x) = I[x > y]
#g2(y) = I[x > 1060]

mean<-c(0.5,0.5)
p<-2

xd1<-c(10,85,209,273,279,324,391,566,852,881,895,954,1101,1393,1669,1823,1941)
nx1=length(xd1)
yd1<-c(21,38,39,51,77,185,524,610,612,677,798,899,946,1010,1074,1147,1154,1329,1484,1602,1952)
ny1=length(yd1)

wxd1new<-c(2.267983, 1.123600, 1.121683, 1.121683, 1.121683, 1.121683, 1.121683,
 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.261740, 2.912753,
 2.912753, 2.912753)
muvec<-c(0.08835785, 0.04075290, 0.04012084, 0.04012084, 0.04012084, 0.04012084,
 0.04012084, 0.03538020, 0.03389263, 0.03389263, 0.03389263, 0.03322693, 0.04901516,
 0.05902008, 0.13065491, 0.13065491, 0.13065491)

wyd1new<-c(1.431653, 1.431653, 1.431653, 1.431653, 1.431653, 1.438453, 1.079955, 1.080832,
 1.080832, 1.080832, 1.080832, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000, 1.000000,
 1.222883, 1.227865, 1.739636, 5.809616)
nuvec<-c(0.04249966, 0.04249966, 0.04249966, 0.04249966, 0.04249966, 0.04316922, 0.03425722,
 0.03463312, 0.03463312, 0.03463312, 0.03463312, 0.03300598, 0.03300598, 0.03333333,
 0.03333333, 0.03382827, 0.03382827, 0.04136800, 0.04229270, 0.05992020, 0.22762676)


H1u<-matrix(NA,nrow=nx1,ncol=ny1)
H2u<-matrix(NA,nrow=nx1,ncol=ny1)
for (i in 1:nx1) {
   for (j in 1:ny1) {
        H1u[i,j]<-(xd1[i]>yd1[j])
        H2u[i,j]<-(xd1[i]>1060) } }
Hu=matrix(c(H1u,H2u),nrow=nx1,ncol=p*ny1)
for (k in 1:p) {
     M1 <- matrix(mean[k], nrow=nx1, ncol=ny1)
     Hu[,((k-1)*ny1+1):(k*ny1)] <- Hu[,((k-1)*ny1+1):(k*ny1)] - M1}
Hmu <- matrix(NA,nrow=p, ncol=ny1*nx1)
Hnu <- matrix(NA,nrow=p, ncol=ny1*nx1) 
for (i in 1:p) {
   for (k in 1:nx1) {
        Hmu[i, ((k-1)*ny1+1):(k*ny1)] <-  Hu[k,((i-1)*ny1+1):(i*ny1)] } }
for (i in 1:p) {
   for (k in 1:ny1) {
        Hnu[i,((k-1)*nx1+1):(k*nx1)] <- Hu[(1:nx1),(i-1)*ny1+k]} }

el2.test.wtm(xd1,yd1,wxd1new, wyd1new, muvec, nuvec, Hu, Hmu,
  Hnu, p, mean, maxit=10)

#muvec1
# [1] 0.08835789 0.04075290 0.04012083 0.04012083 0.04012083 0.04012083 0.04012083
# [8] 0.03538021 0.03389264 0.03389264 0.03389264 0.03322693 0.04901513 0.05902002
# [15] 0.13065495 0.13065495 0.13065495

#nuvec1
# [1] 0.04249967 0.04249967 0.04249967 0.04249967 0.04249967 0.04316920 0.03425722
# [8] 0.03463310 0.03463310 0.03463310 0.03463310 0.03300597 0.03300597 0.03333333
# [15] 0.03333333 0.03382827 0.03382827 0.04136801 0.04229269 0.05992018 0.22762677

#  $lam
#        [,1]      [,2]
#  [1,] 8.9549 -10.29119

Computes maximium-likelihood probability jumps for a single mean-type hypothesis, based on two independent uncensored samples

Description

This function computes the maximum-likelihood probability jumps for a single mean-type hypothesis, based on two samples that are independent, uncensored, and weighted. The target function (Lagrangian) for the maximization is the constrained log(empirical likelihood) which can be expressed as,

dxi=1wxilogμi+dyj=1wyjlogνjη(1dxi=1μi)δ(1dyj=1νj)λdxi=1dyj=1(g(xi,yj)mean)μiνj\sum_{dx_i=1} wx_i \log{\mu_i} + \sum_{dy_j=1} wy_j \log{\nu_j} - \eta ( 1 - \sum_{dx_i=1} \mu_i ) - \delta ( 1 -\sum_{dy_j=1} \nu_j ) - \lambda \sum_{dx_i=1} \sum_{dy_j=1} ( g(x_i,y_j)- mean ) \mu_i \nu_j

where the variables are defined as follows:

xx is a vector of data for the first sample

yy is a vector of data for the second sample

wxwx is a vector of estimated weights for the first sample

wywy is a vector of estimated weights for the second sample

μ\mu is a vector of estimated probability jumps for the first sample

ν\nu is a vector of estimated probability jumps for the second sample

Usage

el2.test.wts(u,v,wu,wv,mu0,nu0,indicmat,mean,lamOld=0)

Arguments

u

a vector of uncensored data for the first sample

v

a vector of uncensored data for the second sample

wu

a vector of estimated weights for u

wv

a vector of estimated weights for v

mu0

a vector of estimated probability jumps for u

nu0

a vector of estimated probability jumps for v

indicmat

a matrix [g(ui,vj)mean][g(u_i,v_j)-mean] where g(u,v)g(u, v) is a user-chosen function

mean

a hypothesized value of E(g(u,v))E(g(u,v)), where EE indicates “expected value.”

lamOld

The previous solution of lambda, used as the starting point to search for new solution of lambda.

Details

This function is called by el2.cen.EMs. It is listed here because the user may find it useful elsewhere.

The value of meanmean should be chosen between the maximum and minimum values of (ui,vj)(u_i,v_j); otherwise there may be no distributions for uu and vv that will satisfy the the mean-type hypothesis. If meanmean is inside this interval, but the convergence is still not satisfactory, then the value of meanmean should be moved closer to the NPMLE for E(g(u,v))E(g(u,v)). (The NPMLE itself should always be a feasible value for meanmean.) The calculations for this function are derived in Owen (2001).

Value

el2.test.wts returns a list of values as follows:

u

the vector of uncensored data for the first sample

wu

the vector of weights for uu

jumpu

the vector of probability jumps for uu that maximize the weighted empirical likelihood

v

the vector of uncensored data for the second sample

wv

the vector of weights for vv

jumpv

the vector of probability jumps for vv that maximize the weighted empirical likelihood

lam

the value of the Lagrangian multipler found by the calculations

Author(s)

William H. Barton <[email protected]> and modified by Mai Zhou.

References

Owen, A.B. (2001). Empirical Likelihood. Chapman and Hall/CRC, Boca Raton, pp.223-227.

Examples

u<-c(10, 209, 273, 279, 324, 391, 566, 785)
v<-c(21, 38, 39, 51, 77, 185, 240, 289, 524)
wu<-c(2.442931, 1.122365, 1.113239, 1.113239, 1.104113, 1.104113, 1.000000, 1.000000)
wv<-c( 1, 1, 1, 1, 1, 1, 1, 1, 1)
mu0<-c(0.3774461, 0.1042739, 0.09649724, 0.09649724, 0.08872055, 0.08872055, 0.0739222, 0.0739222)
nu0<-c(0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1095413, 0.1287447,
 0.1534831)
mean<-0.5

#let fun=function(x,y){x>=y}
indicmat<-matrix(nrow=8,ncol=9,c(
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5, 
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5, -0.5,  0.5,  0.5,  0.5,  0.5,  0.5,  0.5,
-0.5, -0.5, -0.5, -0.5,  0.5,  0.5,  0.5,  0.5,
-0.5, -0.5, -0.5, -0.5, -0.5, -0.5,  0.5,  0.5))
el2.test.wts(u,v,wu,wv,mu0,nu0,indicmat,mean)

# jumpu
# [1] 0.3774461, 0.1042739, 0.09649724, 0.09649724, 0.08872055, 0.08872055, 0.0739222, 0.0739222

# jumpv
# [1] 0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1013718, 0.1095413, 0.1287447,
# [9] 0.1534831

# lam
# [1] 7.055471