Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the specificity Sp as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A new test was compared with the reference standard in a study (see the 2 × 2 table). Find the positive predictive value PPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A test has a sensitivity of 61% and a specificity of 74%. Find the negative likelihood ratio LR−. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A test has a sensitivity of 82% and a specificity of 60%. Find the negative likelihood ratio LR−. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 99% and specificity 89%. The prevalence of the disease is 27%. How many people with the disease are missed by the test (false negatives, FN)?
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 38% in relative terms (RRR = 38%). In a patient group the risk without treatment (CER) is 17% over five years. Find the number needed to treat NNT for five years to prevent one event. Round up to a whole number of patients.
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