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 town has 23 000 inhabitants. At the start of a year, 500 of them have a chronic disease. During the year, 55 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 test has a sensitivity of 70% and a specificity of 93%. Find the negative likelihood ratio LR−. Round to two decimal places.
Practice exercise (made-up values, not clinical guidance). In a randomised trial, 200 patients received a new treatment and 260 received the control treatment. The table shows how many in each group had a side effect. Find the number needed to harm NNH: how many patients must be treated for one extra patient to have the side effect? Round up to a whole number of patients.
Practice exercise (made-up values, not clinical guidance). A screening test has a sensitivity of 70% and a specificity of 84%. It is used in a population where the prevalence is 0.5%. Find the positive predictive value PPV as a percentage. Round to one decimal place.
Practice exercise (made-up values, not clinical guidance). 10 000 people are screened with a test of sensitivity 96% and specificity 92%. The prevalence of the disease is 30%. How many people with the disease are missed by the test (false negatives, FN)?
Full step-by-step solutions: practise this topic on examproblems.com.