ExProb | R Documentation |
For an orm
object ExProb
generates a function for computing the
estimates of the function Prob(Y>=y) given one or more values of the
linear predictor using the reference (median) intercept. This
function can optionally be evaluated at only a set of user-specified
y
values, otherwise a right-step function is returned. There
is a plot method for plotting the step functions, and if more than one
linear predictor was evaluated multiple step functions are drawn.
ExProb
is especially useful for nomogram
. Survival
generates a similar function but for computing survival probabilities Prob(Y>y)
and adding an origin of zero. Plotting of survival curves is done with a
survplot
method. Survival.orm
merely calls ExProb.orm
with argument survival=TRUE
. For survival estimation when interval
censoring is present, times are taken as interval midpoints with intervals
corresponding to intercepts in the model.
Optionally a normal approximation (normality for the linear predictor) for a confidence
interval for exceedance probabilities will be computed, if
conf.int > 0
is specified to the function generated from calling
ExProb
or Survival
. For ExProb
, a "lims"
attribute is included
in the result computed by the derived cumulative probability function. For Survival
,
the result is a data frame if conf.int
is specified or both time and the requested
linear predictor are varying. In the data frame the limits are variables lower
and upper
.
ExProb(object, ...)
## S3 method for class 'orm'
ExProb(object, codes = FALSE, ...)
## S3 method for class 'ExProb'
plot(x, ..., data=NULL,
xlim=NULL, xlab=x$yname, ylab=expression(Prob(Y>=y)),
col=par('col'), col.vert='gray85', pch=20,
pch.data=21, lwd=par('lwd'), lwd.data=lwd,
lty.data=2, key=TRUE)
## S3 method for class 'orm'
Survival(object, ...)
object |
a fit object from |
codes |
if |
... |
ignored for |
data |
Specify |
x |
an object created by running the function created by |
xlim |
limits for x-axis; default is range of observed |
xlab |
x-axis label |
ylab |
y-axis label |
col |
color for horizontal lines and points |
col.vert |
color for vertical discontinuities |
pch |
plotting symbol for predicted curves |
lwd |
line width for predicted curves |
pch.data , lwd.data , lty.data |
plotting parameters for data |
key |
set to |
ExProb
and Survival
return an R function. Running the function returns an
object of class "ExProb"
for ExProb
, or a data frame or vector for Survival
.
Frank Harrell and Shengxin Tu
orm
, Quantile.orm
set.seed(1)
x1 <- runif(200)
yvar <- x1 + runif(200)
f <- orm(yvar ~ x1)
d <- ExProb(f)
lp <- predict(f, newdata=data.frame(x1=c(.2,.8)))
w <- d(lp)
s1 <- abs(x1 - .2) < .1
s2 <- abs(x1 - .8) < .1
plot(w, data=data.frame(x1=c(rep(.2, sum(s1)), rep(.8, sum(s2))),
yvar=c(yvar[s1], yvar[s2])))
qu <- Quantile(f)
abline(h=c(.1,.5), col='gray80')
abline(v=qu(.5, lp), col='gray80')
abline(v=qu(.9, lp), col='green')
## Not run:
Y <- Ocens(dtime, ifelse(censored, Inf, dtime))
f <- orm(Y ~ x, family='loglog')
s <- Survival(f)
s() # all times
s(times=c(1, 3))
d <- data.frame(x=2:4)
s(X=predict(f, d, conf.int=0.95) # all times
s(lp=predict(f, d)) # same surv estimates, no CLs
# use s(..., forcedf=TRUE) to force output to be a data.frame
## End(Not run)
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