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.
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 sensitivity Se as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 760 patients received a new treatment and 900 received the control treatment. The table shows how many in each group had the outcome (an unwanted event such as a stroke). Find the relative risk reduction RRR as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A case-control study compares 150 patients with a disease (cases) and 80 people without it (controls). The table shows how many in each group were exposed to a risk factor. Find the odds ratio OR for the exposure. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 89% and specificity 78%. The prevalence of the disease is 22%. How many false-positive results FP are expected?
Practice exercise (made-up values, not clinical guidance). Without a drug, 23% of patients have a certain side effect during a year. The drug raises this risk with a relative risk of RR = 1.25. Find the number needed to harm NNH: how many patients must take the drug for a year for one extra patient to have the side effect? Round up to a whole number of patients.
Answer key
- 1. Sp = 70 %
- 2. Se = 60.9 %
- 3. RRR = 50 %
- 4. OR = 3.97
- 5. FP = 1716
- 6. NNH = 18
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