EVALUATION OF COHEN’S KAPPA AS TEST OF RELIABILITY BETWEEN COVID-19 PATIENT SURVEYS AND MEDICAL RECORDS

Sammanfattning: Evaluating the statistical properties of Cohen’s κ, this thesis conducts a study of the reliability of patient surveys and medical records for mild cases of Covid-19. Using data collected from Uppsala University Hospital, right-tailed hypothesis testing is performed for the variables Hypertension, Lung disease, Fatigue, Dyspnea and loss of smell and/or taste. Results show only Hypertension rejecting the null hypothesis of low reliability, thus achieving a "Moderate" strength of agreement according to Landis and Koch. Simulating 10000 draws of a multinomial distribution, the thesis finds that the distribution of κ is asymmetric. Simulation of the size-adjusted power of κ shows that the probability of committing Type II errors is significant for the sample sizes of 400 and lower used in the study. In addition, κ appears vulnerable to the effects of sample bias and prevalence and thus risk giving a misleading result. As such,researchers should compare it with the adjusted estimator PABAK if possible.