Objects of the class phm
are output by the function with the same name. Apart from standard methods the function sroc
provides SROC curves and confidence bands for model fits.
1 2 3 4 5 6 7 8 9 10  ## S3 method for class 'phm'
print(x, ...)
## S3 method for class 'phm'
summary(object, level = 0.95, ...)
## S3 method for class 'phm'
sroc(fit, fpr = 1:99/100, ...)
## S3 method for class 'phm'
plot(x, extrapolate = FALSE, confband = TRUE, level = 0.95,
ylim = c(0,1), xlim = c(0,1), sroclty = 1, sroclwd = 1,
confbandlty = 2, confbandlwd = 0.5, ...)

x 
a 
object 
a 
fit 
a 
level 
numeric, the confidence level for calculations of confidence intervals ( 
fpr 
numeric, the false positives rates for which to calculate the predicted sensitivities. 
extrapolate 
logical, should the sroc curve be plotted beyond the observed false positive rates? 
confband 
logical, should confidence bands be plotted? 
ylim 
numeric of length 2, which section of the sensitivities to plot? 
xlim 
numeric of length 2, which section of the false positive rates to plot? 
sroclty 
integer, line type of the SROC curve 
sroclwd 
integer, line width of the SROC curve 
confbandlty 
integer, line type of the SROC curve's confidence band 
confbandlwd 
integer, line width of the SROC curve's confidence band 
... 
arguments to be passed on to other functions 
The SROC curve is derived from the model formula. The confidence bands are calculated from the bounds of the confidence interval for the diagnostic accuracy parameter θ. The parameter and its confidence interval are then also used to calculate the AUC and partial AUC using the formulae
AUC(a,b) = \int_a^bu^θ\mathrm{d}u = \frac{1}{θ+1}[b^{θ+1}a^{θ+1}],
AUC = AUC(0,1)
and
pAUC = \frac{1}{ba}AUC(a,b),
where a is the lower bound of the observed false positive rates and b the upper.
The sroc
function returns a matrix ready for plotting. Each row corresponds to one point in ROC space.
Philipp Doebler <philipp.doebler@googlemail.com>
Holling, H., Boehning D., Boehning, W. (2012) “MetaAnalysis of Diagnostic Studies based upon SROCCurves: a Mixed Model Approach using a Proportional Hazards Model.” Statistical Modelling, 12, 347–375.
phm
1 2 3 4 5 6 7 8 9 10 
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