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 randomised trial, 860 patients received a new treatment and 960 received the control treatment. The table shows how many in each group had a side effect. Find the number needed to harm NNH: how many patients must be treated for one extra patient to have the side effect? Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 810 patients received a new treatment and 390 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the absolute risk reduction ARR as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 98% and specificity 93%. The prevalence of the disease is 29%. How many false-positive results FP are expected?
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 84% and a specificity of 98%. It is used in a population where the prevalence is 2%. Find the positive predictive value PPV as a percentage. Round to one decimal place.
Answer key
- 1. Se = 60 %
- 2. Sp = 88.9 %
- 3. NNH = 2
- 4. ARR = 7.9 %
- 5. FP = 497
- 6. PPV = 46.2 %
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