Methods for Testing Normality of Hydrologic Time Series

Abstract

Statistical methods are applied in all the phases of time series analysis from collecting data to evaluating results in hydrologic studies. Advances in computer technology has enabled most of the scientists/researchers to apply statistical analyses effectively; however, some of the researchers do not check parametric test assumptions, especially the normality assumption (Adeloye and Montaseri, 2002). Many methods of time series analysis depend on the basic assumption that data were sampled from a normal distribution (Madansky, 1988; USEPA, 1996; Thode, 2002). This assumption is very crucial for the reliability of results especially for parametric tests. These days many statistical software packages are available, which include several tests for checking the normality of time series data. However, the important point is to judge which test should be used under what condition (USEPA, 1996).