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.
Practice exercise (made-up values, not clinical guidance). A town has 3500 inhabitants. At the start of a year, 59 of them have a chronic disease. During the year, 37 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). A case-control study compares 220 patients with a disease (cases) and 740 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). In a cohort study, exposed people contributed 1000 person-years with 34 new cases, and unexposed people 6500 person-years with 111 new cases. Find the incidence rate ratio IRR (exposed versus unexposed). Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 76% and specificity 76%. The prevalence of the disease is 4%. How many true-positive results TP are expected?
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 81% and a specificity of 93%. It is used in a population where the prevalence is 10%. Find the negative predictive value NPV as a percentage. Round to one decimal place.
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