En simuleringsstudie på sannolikhet för typ I-fel och styrka hos olika normalitetstest på avrundade data

Sammanfattning: When data is collected sample size and precision in measurements are often limited. In what sense this impacts the size, unadjusted and adjusted power of different normality tests is a relatively unexplored field. Therefore this paper is dedicated to perform a simulation study where these three properties of the normality tests Anderson-Darling, Jarque-Bera and Shapiro-Wilk are examined. The study is based on different combinations of sample sizes and roundings where repeated samples are drawn from both normally and asymmetrically distributed populations. The results from the study indicate that coarser roundings results in increased size and unadjusted power of Anderson-Darling and Shapiro-Wilk, while Jarque-Bera is seemingly unaffected by roundnings. The three tests have in common that a larger sample size leads to an increase in the size, unadjusted and adjusted power of the tests and that roundings have no substantial impact on adjusted power.