specimens

stdtest has been done on everyone, and sampledtest has been done on a stratifed subsample of 275 out of 402 specimens (is NA on the other 127 specimens)

datasets

A standard test is observed on all specimens. We treat the second test (or sampled test) as being conducted on only a stratified sample of specimens. Verification Bias is this situation when the specimens for doing the second (sampled) test is not under investigator control. We treat the total sample as stratified two-phase sampling and use inverse probability weighting. We estimate diagnostic accuracy (category-specific classification probabilities; for binary tests reduces to specificity and sensitivity, and also predictive values) and agreement statistics (percent agreement, percent agreement by category, Kappa (unweighted), Kappa (quadratic weighted) and symmetry tests (reduces to McNemar's test for binary tests)). See: Katki HA, Li Y, Edelstein DW, Castle PE. Estimating the agreement and diagnostic accuracy of two diagnostic tests when one test is conducted on only a subsample of specimens. Stat Med. 2012 Feb 28; 31(5) <doi:10.1002/sim.4422>.

Hormuzd A Katki

CompareTests

Correct for Verification Bias in Diagnostic Accuracy & Agreement

Hormuzd Katki

specimens function

A data frame with 402 observations on the following 3 variables.<dl>
 <dt><code>stratum</code></dt>
<dd>6 strata used for sampling</dd> <dt><code>stdtest</code></dt>
<dd>standard test result available on all specimens</dd> <dt><code>sampledtest</code></dt>
<dd>new test result available only on stratified subsample</dd> 
</dl>

Format

Fictitious data on specimens tested by two methods — specimens

A data frame with 402 observations on the following 3 variables.<dl>
 <dt><code>stratum</code></dt>
<dd>6 strata used for sampling</dd>

 <dt><code>stdtest</code></dt>
<dd>standard test result available on all specimens</dd>

 <dt><code>sampledtest</code></dt>
<dd>new test result available only on stratified subsample</dd>

 
</dl>

specimens: Fictitious data on specimens tested by two methods

Description

Usage

Arguments

Format

Examples