Description Usage Arguments Value METHOD References See Also Examples
Tests if there is a difference between two survival curves based on two samples (X and Y)
with right censored data. More precisely it test whether the probabiliy P(X<Y) is greater
than, lower than or equal to 1/2.
The prior nearignorance Dirichlet Process (IDP) rank sum test is used.
It returns the result of the deicison.
H=1 indicates that the alternative hypothesis is true with posterior
probability greater than level
.
H=0 indicates the hypothesis is not true with posterior greater than level
,
H=2 indicates an indeterminate instance. This means that the decision depends on
the choice of the prior.
1 2 3 4 
formula 
a formula expression of the form 
data 
an optional data frame in which to interpret the variables occurring in the formula. 
groups 
a vector of two element indicating which value of the predictor represents groups 1 and 2. 
s 
sets the value of the prior strength s of the Dirichlet Process. 
alternative 
define the direction of the test:
"greater" –evaluates the hypothesis P(X < Y)>1/2, i.e., returns H=1
if the lower probability of the hypothesis is larger than

exact 
computes the posterior probability if value is TRUE,
or uses a normal approximation if value is FALSE.
If you omit this argument, 
level 
sets the significance level alpha = 1 
display 
determines whether the posterior distributions of P(X<Y) have to be plotted (TRUE) or not (FALSE). 
nsamples 
if 
rope 
introduces a (symmetric) Region of Practical Equivalence (ROPE) around 1/2, i.e., [1/2value,1/2+value]. 
tmax 
whether to consider the difference in survival up to time tmax. NULL is the default and means without limit. 
a list with components:
h 
The decision of the test: H=0 > accept the null hypothesis; H=1 > rejects the null hypothesis; H=2 > indeterminate (a robust decision cannot be made). 
prob 
the probability of the alternatice hypotesis P(X<Y)>1/2
if 
Lower.Cred.Int 
lower HPD credible interval.
Confidence level defined by 
Upper.Cred.Int 
upper HPD credible interval. Confidence level defined by 
alternative 
the direction of the test 
strata 
the number of subjects contained in each group. 
exact 
logical variable saying if the exact posterior distributions
have been computed ( 
This function implements the IDP sumrank test describe in Mangili and others (2014).
Benavoli, A., Mangili, F., Zaffalon, M. and Ruggeri, F. (2014). Imprecise Dirichlet process with application to the hypothesis test on the probability that X < Y. ArXiv eprints, http://adsabs.harvard.edu/abs/2014arXiv1402.2755B.
Mangili, F., Benavoli, A., Zaffalon, M. and de Campos, C. (2014). Imprecise Dirichlet Process for the estimate and comparison of survival functions with censored data.
Surv
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14  data(lung,package='survival')
test <isurvdiff(Surv(time,status)~sex,lung,groups=c(1,2),
alternative = 'two.sided',s=0.5, nsamples=1000)
print(test)
data(Aids2)
fdata < Surv(time, status) ~ T.categ
dataset < Aids2
groups=c("blood","haem")
dataset["time"]<dataset[4]dataset[3]
dataset[5]<as.numeric(unlist(dataset[5]))
test <isurvdiff(fdata,dataset,groups=groups,
alternative = 'greater',s=0.5, nsamples=1000)
print(test)

Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.