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 specificity Sp as a percentage. Round to one decimal place.
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 case-control study compares 270 patients with a disease (cases) and 390 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 74% and specificity 76%. The prevalence of the disease is 4%. How many false-positive results FP are expected?
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 76% and a specificity of 86%. It is used in a population where the prevalence is 3%. Find the positive predictive value PPV as a percentage. Round to one decimal place.
Answer key
- 1. Acc = 64.7 %
- 2. Sp = 62 %
- 3. LR− = 0.27
- 4. OR = 1.62
- 5. FP = 2304
- 6. PPV = 14.4 %
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