chisqcens1: General chi-squared statistics for right-censored data.

In GofCens: Goodness-of-Fit Methods for Right-Censored Data

Description

chisqcens1 computes the general chi-squared statistic for right-censored data introduced by Kim (1993).

Usage

chisqcens1(times, cens = rep(1, length(times)), M, 
           distr = c("exponential", "gumbel", "weibull", "normal", 
                     "lognormal", "logistic", "loglogistic", "beta", 
                     "uniform"), 
           betaLimits = c(0, 1), igumb = c(10, 10), degs = 4, 
           params = list(shape = NULL, shape2 = NULL, location = NULL, 
                         scale = NULL))

Arguments

times	Numeric vector of times until the event of interest.
cens	Status indicator (1, exact time; 0, right-censored time). If not provided, all times are assumed to be exact.
M	Number indicating the number of cells that will be considered.
distr	A string specifying the name of the distribution to be studied. The possible distributions are the exponential ("exponential"), the Weibull ("weibull"), the Gumbel ("gumbel"), the normal ("normal"), the lognormal ("lognormal"), the logistic ("logistic"), the loglogistic ("loglogistic"), the beta ("beta"), and the uniform ("uniform") distribution.
betaLimits	Two-components vector with the lower and upper bounds of the Beta distribution. This argument is only required, if the beta distribution is considered.
igumb	Two-components vector with the initial values for the estimation of the Gumbel distribution parameters.
degs	Integer indicating the number of decimal places of the numeric results of the output.
params	List specifying the parameters of the theoretical distribution. By default, parameters are set to NULL and estimated with the maximum likelihood method. This argument is only considered, if all parameters of the studied distribution are specified.

Details

The function implements the test introduced by Kim (1993) and returns the value of the test statistic.

The cell boundaries of the test are obtained via the quantiles, which are based on the Kaplan-Meier estimate of the distribution function. In the presence of right-censored data, it is possible that not all quantiles are estimated, and in this case, the value of M provided by the user is reduced.

The parameter estimation is acomplished with the fitdistcens function of the fitdistrplus package.

Value

A list containing the following components

Statistic	Value of the test statistic.
Distribution	Null distribution.
Parameters	The values of the parameters of the null distribution. If the user has set the parameters manually, these will be the returned parameters, otherwise the maximum likelihood estimates are returned.
CellNumber	Vector with two values: the original cell number introduced by the user and the final cell number used.

Author(s)

K. Langohr, M. Besalú, G. Gómez.

References

J. H. Kim. Chi-Square Goodness-of-Fit Tests for Randomly Censored Data. In: The Annals of Statistics, 21 (3) (1993), 1621-1639.

See Also

chisqcens2 for the computation of the p-value.

Examples

# Complete data
set.seed(123)
chisqcens1(time = rgumbel(1000, 12, scale = 4), M = 8, distr = "gumbel")

# Censored data
library(survival)
chisqcens1(aml$time, aml$status, M = 6, distr = "weibull")

data(nba)
chisqcens1(nba$survtime, nba$cens, 10, "logis", degs = 2)
chisqcens1(nba$survtime, nba$cens, 10, "beta", betaLimits = c(0, 70))

GofCens documentation built on Jan. 6, 2022, 1:06 a.m.