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 positive predictive value PPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). A town has 39 500 inhabitants. At the start of a year, 350 of them have a chronic disease. During the year, 542 more people are newly diagnosed (assume nobody moves away or dies). Find the cumulative incidence CI over the year per 1000 people at risk. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 870 patients received a new treatment and 430 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). A case-control study compares 130 patients with a disease (cases) and 380 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 88% and specificity 78%. The prevalence of the disease is 14%. How many false-positive results FP are expected?
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 74% and specificity 93%. The prevalence of the disease is 3%. How many false-positive results FP are expected?
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