Description Usage Arguments Details Value Author(s) See Also Examples
This function performs the CGR-CUSUM procedure
described in ARTICLE UNDER REVIEW FOR PUBLICATION. For detection purposes, it is sufficient
to only determine the value of the chart at the times of failure. This can be
achieved by leaving ctimes
empty.
1 2 3 4 5 6 7 8 9 10 11 |
data |
and optionally additional covariates used for risk-adjustment. |
coxphmod |
(optional) a cox proportional hazards regression model as produced by
the function
|
cbaseh |
a function which returns the non risk-adjusted cumulative
baseline hazard H_0(t). If |
ctimes |
(optional) vector of construction times at which the value of the chart should be determined. When not specified, the chart is constructed at all failure times. |
h |
(optional) value of the control limit. The chart will only be constructed until the value of the control limit has been reached or surpassed. |
stoptime |
(optional) time after which the value of the chart should no longer be determined. Default = max(failure time). Useful when ctimes has not been specified. |
C |
(optional) a numeric value indicating how long after entering the study
patients should no longer influence the value of the chart. This is
equivalent to right-censoring every observation at time |
pb |
(optional) boolean indicating whether a progress bar should be shown. Default = FALSE |
cmethod |
One of the following:
|
The CGR-CUSUM can be used to test for a change of unknown positive fixed size θ in the subject-specific hazard rate from h_i(t) to h_i(t) exp(θ) starting from some unknown patient ν. The starting time of the first patient which had an increase in failure rate as well as the estimated increase in the hazard rate are also given in the output. The CGR-CUSUM is determined as:
max{1<=ν<=n} (θ_{>=ν}(t)N_{>=ν}(t)) - (exp(θ_{>=ν}(t))-1) Λ_{>=ν}(t))
with
N_{>=ν}(t) = ∑_{i>=ν} N_i(t)
with N_i(t) the counting process for the failure at time t of subject i and
Λ_{>=ν}(t) = ∑_{i>=ν}Λ_i(t)
the with Λ_i(t) the cumulative intensity of subject i at time t.
An object of class "cgrcusum" containing:
CGR
: a data.frame with named columns:
$time (time of construction),
$value (value of the chart at $time),
$exp_theta_t (value of MLE e^(θ_t)),
$S_nu (time from which patients are considered for constructing the chart)
call
: Contains the call
used to obtain output;
stopind
: (only if h specified) Boolean indicating whether the chart was stopped by the provided value of h;
h
: Specified value for the control limit;
There are plot
and
runlength
methods for "cgrcusum" objects.
Daniel Gomon
plot.cgrcusum
, runlength.cgrcusum
Other qcchart:
bercusum()
,
bkcusum()
,
funnelplot()
1 2 3 4 5 6 7 8 9 | require(survival)
tdat <- subset(surgerydat, Hosp_num == 1)
tcbaseh <- function(t) chaz_exp(t, lambda = 0.01)
varsanalysis <- c("age", "sex", "BMI")
exprfit <- as.formula(paste("Surv(survtime, censorid) ~" ,paste(varsanalysis, collapse='+')))
tcoxmod <- coxph(exprfit, data= surgerydat)
#Alternatively, cbaseh can be left empty when specifying coxphmod through coxph()
cgr <- cgrcusum(data = tdat, coxphmod = tcoxmod, cbaseh = tcbaseh, pb = TRUE)
plot(cgr)
|
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