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Reliability & validity of microbiological test for influenza

A study was conducted to assess the reliability of a quick test to identify subject who have been infected with an influenza virus. A total of 432 subjects are enrolled. A rapid flu test is administered. In addition, a blood sample is taken.

Of the 432 subjects, both tests were positive in 40 instances, both were negative in 321. The rapid flu test was positive and the blood test was negative in 37 instances, and the rapid flu test was negative and the blood test was positive in 34 instances.

1. Estimate the reliability of the test by estimating the following
a. percent agreement
b. percent positive agreement
c. Kappa Statistic

2. Estimate the validity of the rapid flu test by estimating the following:
a. sensitivity
b. specificity
c. Youden's J-Statistic.

Solution Preview

Reliability

Reliability is the degree of consistency of the measure. Reliability is not enough; a test must also be valid for its use.
If test scores are to be used to make accurate inferences about an examinee's ability, they must be both reliable and valid. Reliability is a prerequisite for validity and refers to the ability of a test to measure a particular trait or skill consistently.

One of the more commonly used measures of interrater reliability is kappa. Kappa takes into ...

Solution Summary

This solution finds the reliability and validity of the rapid flu test for influenza using different characters such as kappa statistics, sensitivity, specificity, etc of the test employed.

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