Alexander Mertens, Christopher Brandl, Philipp Przybysz, David Koch-Körfges, Christopher M Schlick
Design recommendations for the creation of icons for the elderly
Work (Reading, Mass.)
many diagnostic tests currently performed around world detect sarscov2 infection positive negative test results one hundred percent accurate farreaching consequences false positives test positive uninfected false negatives test negative infected positivenegative result necessarily mean test subject actually infectednoninfected article two objectives 1 explain important characteristics diagnostic tests binary outcome 2 point problems phenomena interpretation diagnostic tests basis different scenarios presentation basic concepts quality diagnostic test sensitivity specificity pretest probability prevalence test group calculation including formulas important quantities basic scenario sensitivity 100 specificity 988 pretest probability 10 10 infected persons per 1000 tested 1000 diagnostic tests statistical mean 22 positive cases 10 truepositive positive predictive probability 457 prevalence calculated 221000 tests overestimates actual prevalence 101000 tests factor 22 cases negative test outcome true negative prevalence strong influence positive negative predictive value phenomenon occurs even otherwise good test values sensitivity specificity prevalence 5 infected persons per 10000 005 positive predictive probability drops 40 lower specificity amplifies effect especially small numbers infected persons sensitivity specificity 100 diagnostic tests always errorprone prevalence infected persons low large number false positive results expected even test good quality high sensitivity especially high specificity accompanied low positive predictive values e positive tested persons infected false positive test result first test clarified carrying second test