Question

A new type of blood test has been developed to screen people for HPV, a virus...

A new type of blood test has been developed to screen people for HPV, a virus than can cause cervical cancer in women and oral cancer in both sexes. A total of 100 people tested positive for the virus, and of these subjects there were 73 who actually had HPV according to the standard microbiology examination. Of those who tested negative for the virus (N=624), there were 618 who were truly negative by the standard examination. Determine the sensitivity and specificity of the new blood test.

What is the sensitivity of the new blood test? ____

What is its specificity? _____

Explain why you would or wouldn’t support using this test in practice.

Math   Statistics-And-Probability   
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Answer #1
Positive test result Negative test result Total
Virus is present 73 6 79
Virus is not present 27 618 645
Total 100 624 724

Sensitivity = Number of true positives/Total number of cases in which virus is present

= 73/79

= 0.924

Specificity = Number of true negative / Number of cases in which virus is not present = 618/645

= 0.958

The test will not detect the presence of disease 7.6% of time as the sensitivity is only 92.4%. This result is not satisfactory and hence it is not recommended to use this test in practice.

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