# pv.wgs: Weighted Generalized Score Statistic for Comparison of... In DTComPair: Comparison of Binary Diagnostic Tests in a Paired Study Design

## 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

 `1` ```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.

`pv.gs` and `pv.rpv`.

## Examples

 ```1 2 3 4 5 6 7 8``` ```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"] ```

### Example output

```Loading required package: gee
y2   0   1
d y1
0 0     155  22
1      53  31
1 0      32  22
1      78 319
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

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)"
\$ppv
\$ppv\$test1
 0.8253638

\$ppv\$test2
 0.8654822

\$ppv\$diff
 0.04011841

\$ppv\$test.statistic
 5.465887

\$ppv\$p.value
 0.0193912

\$npv
\$npv\$test1
 0.7662338

\$npv\$test2
 0.6540881

\$npv\$diff
 0.1121457

\$npv\$test.statistic
 16.5354

\$npv\$p.value
 4.775012e-05

\$method
 "weighted generalized score statistic (wgs)"

\$p.value
 0.0193912
```

DTComPair documentation built on May 2, 2019, 6:53 a.m.