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 sensitivity Se as a percentage. Round to one decimal place.
Evidence-based practice statistics worksheet with answers
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 accuracy Acc as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a cohort, groups of people were followed for different lengths of time (see the table: number of people and years of follow-up for each). During follow-up, 8 new cases occurred. Find the incidence rate IR per 1000 person-years. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A test has a sensitivity of 93% and a specificity of 60%. Find the positive likelihood ratio LR+. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 94% and a specificity of 97%. It is used in a population where the prevalence is 30%. Find the positive predictive value PPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 19% in relative terms (RRR = 19%). In a patient group the risk without treatment (CER) is 21% 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.
Answer key
- 1. Se = 84 %
- 2. Acc = 81.7 %
- 3. IR = 4.7 per 1000 person-years
- 4. LR+ = 2.33
- 5. PPV = 93.1 %
- 6. NNT = 26
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