R: Weighted Generalized Score Statistic for Comparison of...
pv.wgs
R Documentation
Weighted Generalized Score Statistic for Comparison of Predictive Values
Description
Performs a test for differences in (positive and negative) predictive values of two binary diagnostic tests using a weighted generalized score statistic proposed by Kosinski (2013).
Usage
pv.wgs(tab)
Arguments
tab
An object of class tab.paired.
Value
A list containing:
ppv
A list with test1 (the positive predictive value of test 1), test2 (the positive predictive value of test 2), diff (the difference in positive predictive values, computed as test2 - test1, the test.statistic and the corresponding p.value.
npv
A list with test1 (the negative predictive value of test 1), test2 (the negative predictive value of test 2), diff (the difference in negative predictive values, computed as test2 - test1, the test.statistic and the corresponding p.value.
method
The name of the method used to compare predictive values, here “weighted generalized score statistic (wgs)”.
References
Kosinski, A.S. (2013). A weighted generalized score statistic for comparison of predictive values of diagnostic tests. Stat Med, 32(6):964-77.
See Also
pv.gs and pv.rpv.
Examples
data(Paired1) # Hypothetical study data
ftable(Paired1)
paired.layout <- tab.paired(d=d, y1=y1, y2=y2, data=Paired1)
paired.layout
wgs.results <- pv.wgs(paired.layout)
str(wgs.results)
wgs.results
wgs.results$ppv["p.value"]
Results
R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)
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Type 'demo()' for some demos, 'help()' for on-line help, or
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> library(DTComPair)
Loading required package: gee
Loading required package: PropCIs
> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/DTComPair/pv.wgs.Rd_%03d_medium.png", width=480, height=480)
> ### Name: pv.wgs
> ### Title: Weighted Generalized Score Statistic for Comparison of
> ### Predictive Values
> ### Aliases: pv.wgs
>
> ### ** Examples
>
> data(Paired1) # Hypothetical study data
> ftable(Paired1)
y2 0 1
d y1
0 0 155 22
1 53 31
1 0 32 22
1 78 319
> paired.layout <- tab.paired(d=d, y1=y1, y2=y2, data=Paired1)
> paired.layout
Two binary diagnostic tests (paired design)
Test1: 'y1'
Test2: 'y2'
Diseased:
Test1 pos. Test1 neg. Total
Test2 pos. 319 22 341
Test2 neg. 78 32 110
Total 397 54 451
Non-diseased:
Test1 pos. Test1 neg. Total
Test2 pos. 31 22 53
Test2 neg. 53 155 208
Total 84 177 261
> wgs.results <- pv.wgs(paired.layout)
> str(wgs.results)
List of 3
$ ppv :List of 5
..$ test1 : num 0.825
..$ test2 : num 0.865
..$ diff : num 0.0401
..$ test.statistic: num 5.47
..$ p.value : num 0.0194
$ npv :List of 5
..$ test1 : num 0.766
..$ test2 : num 0.654
..$ diff : num 0.112
..$ test.statistic: num 16.5
..$ p.value : num 4.78e-05
$ method: chr "weighted generalized score statistic (wgs)"
> wgs.results
$ppv
$ppv$test1
[1] 0.8253638
$ppv$test2
[1] 0.8654822
$ppv$diff
[1] 0.04011841
$ppv$test.statistic
[1] 5.465887
$ppv$p.value
[1] 0.0193912
$npv
$npv$test1
[1] 0.7662338
$npv$test2
[1] 0.6540881
$npv$diff
[1] 0.1121457
$npv$test.statistic
[1] 16.5354
$npv$p.value
[1] 4.775012e-05
$method
[1] "weighted generalized score statistic (wgs)"
> wgs.results$ppv["p.value"]
$p.value
[1] 0.0193912
>
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> dev.off()
null device
1
>