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 specificity Sp 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, 4 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). In a cohort study, exposed people contributed 1500 person-years with 61 new cases, and unexposed people 3500 person-years with 95 new cases. Find the incidence rate ratio IRR (exposed versus unexposed). Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 70% and specificity 95%. The prevalence of the disease is 16%. How many positive results n₊ are expected in total?
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 95% and a specificity of 88%. It is used in a population where the prevalence is 1%. Find the negative predictive value NPV as a percentage. Round to one decimal place.
Answer key
- 1. Se = 90 %
- 2. Sp = 60 %
- 3. IR = 7.4 per 1000 person-years
- 4. IRR = 1.5
- 5. n₊ = 1540
- 6. NPV = 99.9 %
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