Question

A new screening test for COVID-19 was administered to 1,000 adults at a large medical center in Texas. The results showed that 152 out of 160 diagnosed cases of COVID-19 were correctly identified by the screening test. Of the 840 individuals without COVID-19, the screening test correctly identified 714. Based upon this information:

1. Calculate the test's sensitivity, specificity, and the positive and negative predictive values.

2. Calculate the prevalence rate of COVID-19 in this population and the accuracy of the screening test.

Answer 1

from given data:

	tested positive	tested negative	total
have COVID-19	152	8	160
not have COVID-19	126	714	840
total	278	722	1000

1)

test's sensitivity =tested positive given have COVID-19 =152/160=0.95

specificity =tested negative given not have =714/840 =0.85

positive predictive value =true positive/total positive =152/278 =0.5468

negative predictive value =true negative/total negative =714/722 =0.9889

2)

prevalence rate of COVID-19 =160/1000 =0.16

accuracy =correct result/total result =(152+714)/1000 =0.866