Calculation-Bayes Theorem! Prevalence of the disease matters and the accuracy of the test. Accuracy of a test means that IF a person has Covid, that's the percent chance that person will test positive or IF a person does not have Covid, that's the percent chance that person will test negative. b) Let's look at the numbers of if the Covid Test is 98% accurate and Covid is in 10% of the population. For ease, let's calculate using a population of 5000 people: Disease Present Test Negative Test Positive 98% accurate: Disease Not Present 98% accurate: Totals: Totals: 10% of population (5000): 500 people 90% of population (5000): 4500 people 5000 people c) Now if 1% of the population has Covid: Disease Present Disease Not Present Totals: Test Positive Test Negative Totals: 5000 people d) What is the likelihood that given your Covid test reads positive, you have received a false positive? 10%: 1%: