Question

g The prostate specific antigen (PSA) test was used to screen for prostate cancer in 290 men with biopsy-proven (gold standard) prostate cancer and in 516 age- and race-matched men all of whom showed no evidence of cancer at biopsy. The results of the PSA test yielded positive results for 136 men with biopsy-proven prostate cancer and in 165 men with no evidence of cancer at biopsy. What is the specificity of the physical examination?

Answer 1

Answer: The specific of the physical examination is 0.68

Explanation: Specificity is based on the individuals that does not show any sign of the disease when weighed using the medical criterion or gold standard.

Specificity is calculated as the number of persons that are not infected and does not show any sign of the disease divided by the total number of persons that does not show any sign of the disease.

From the Analysis 516 persons doesn't show any sign of the disease when weighed with the medical criterion or gold standard. That means our main concentration is on the 516 person.

Among the 516 person's 165 persons were positive of the disease when diagnosed.

Therefore the number of persons that are not infected is 516 - 165 = 351.

Therefore;

Specificity = 351 ÷ 516 = 0.68

This means that the medical criterion for physical examinations of people that are infected by the disease is not a perfect means of determining people with the infection.