Statistical and Visual Comparison of Water Quality Changes Caused by a Large River Restoration Project

摘要

This article presents a statistical and visual comparison of water quality changes caused by a large river restoration project. Since water quality data are often shown as a non-normal distribution with high seasonal variations, appropriate statistical methods should be selected according to data characteristics for accurate scientific decision-making. In this study, a normality test was first performed using the Shapiro–Wilk test and two statistical comparison tests were then performed, including the paired iT -test and the sign-test. Seasonality was considered by comparing monthly data pairs. In addition, a diagonal pair comparison plot was proposed as a visual comparison method. This plot is a graphic data display, where monthly paired water quality is represented by iX –iY coordinates. From this study, it was concluded that the series of statistical and visual methods would be suggested for comparison of non-normally distributed water quality with high seasonal variations.