Summarizing and presenting numerical data

Abstract

Scientific hypothesis and type of the study define variab les that have to be measured. Measurements aredetermined by fourdistinctsca les of measurement; no minal, ordinal, interval and ratio, produci ng two distinct types of data: categorical and numeri cal. Numerical data are usually summarized and pre sen ted by dis tribution, measures of central tendency and disper sion. For normally dis tributed data, arithmetic mean and standardde viation are used. For data not normally distributed, median with data range (minimum to maximum, interquartile range or percentile range) and mode are used. Commonly used gra ph types in des criptive statistics for numerical da ta presentation areerror barand box-and-whisker plots. Outliers are values that are numerically distant from the rest of the data and must berecognized.