IntSurvDiff {PwrGSD} | R Documentation |
Computes a two sample weighted integrated survival function log-rank statistic with events weighted according to one of the available weighting function choices
IntSurvDiff(formula = formula(data), data = parent.frame(), WtFun = c("FH", "SFH", "Ramp"), param = c(0, 0), sided = c(2, 1), subset, na.action, w = FALSE)
formula |
a formula of the form Surv(Time, Event) ~ arm where arm
is a dichotomous variable with values 0 and 1. |
data |
a dataframe |
WtFun |
a selection from the available list: “FH” (Fleming-Harrington),
“SFH” (stopped Fleming-Harrington) or “Ramp”. See param in
the following line. |
param |
Weight function parameters. Length and interpretation depends upon
the selected value of WtFun :
If WtFun==\dQuote{FH} then param is a length 2 vector specifying the power of the
pooled (across arms) kaplan meier estimate and its complement.
If WtFun==\dQuote{SFH} then param is a length 3 vector with first two components
as in the “FH” case, and third component the time (in the same units as the time
to event) at which the “FH” weight function is capped off at its current value.
If WtFun==\dQuote{SFH} then param is of length 1 specifying the time (same units
as time to event) at which events begin to get equal weight. The “Ramp” weight
function is a linearly increasing deterministic weight function which is capped off at 1
at the user specified time. |
sided |
One or Two sided test? Set to 1 or 2 |
subset |
Analysis can be applied to a subset of the dataframe based upon a logical expression in its variables |
na.action |
Method for handling NA values in the covariate, arm |
w |
currently no effect |
An object of class survtest
containing components
pn |
sample size |
wttyp |
internal representation of the WtFun argument |
par |
internal representation of the param argument |
time |
unique times of events accross all arms |
nrisk |
number at risk accross all arms at each event time |
nrisk1 |
Number at risk in the experimental arm at each event time |
nevent |
Number of events accross all arms at each event time |
nevent1 |
Number of events in the experimental arm at each event time |
wt |
Values of the weight function at each event time |
pntimes |
Number of event times |
stat |
The un-normalized weighted log-rank statistic, i.e. the summed weighted observed minus expected differences at each event time |
var |
Variance estimate for the above |
pu0 |
person units of follow-up time in the control arm |
pu1 |
person units of follow-up time in the intervention arm |
n0 |
events in the control arm |
n1 |
events in the intervention arm |
n |
sample size, same as pn |
call |
the call that created the object |
Grant Izmirlian <izmirlian@nih.gov
Weiand S, Gail MH, James BR, James KL. (1989). A family of nonparametric statistics for comparing diagnostic makers with paired or unpaired data. Biometrika 76, 585-592.
library(PwrGSD) data(lung) fit.isd <- IntSurvDiff(Surv(time, I(status==2))~I(sex==2), data=lung, WtFun="SFH", param=c(0,1,300))