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.
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 prevalence in the study p as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 270 patients received a new treatment and 910 received the control treatment. The table shows how many in each group had a side effect. Find the relative risk RR of the event with treatment. Round to two decimal places.
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 negative likelihood ratio LR−. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). A treatment reduces the risk of an event by 31% in relative terms (RRR = 31%). In a patient group the risk without treatment (CER) is 4% 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.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 86% and specificity 82%. The prevalence of the disease is 27%. How many positive results n₊ are expected in total?
Answer key
- 1. Acc = 64.3 %
- 2. p = 3.3 %
- 3. RR = 1.3
- 4. LR− = 0.37
- 5. NNT = 81
- 6. n₊ = 3636
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