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USER GUIDE Prepared by Francis Chiew and Lionel Siriwardena CRC for Catchment H

USER GUIDE Prepared by Francis Chiew and Lionel Siriwardena CRC for Catchment Hydrology www.toolkit.net.au/trend Document History Date Author Revision Description of Change February 2004 Francis Chiew 0.1 Basic User Guide for Modelling School June 2004 Robert Argent 1.0 Creation of User Guide from Notes July 2004 Francis Chiew 1.0.2b First version of User Guide. This applies to version 1.02b (beta) of the Trend software February 2005 Francis Chiew 1.0.2 User Guide for first full release of TREND version 1.0.2 (1.0.2 and 1.0.2b are similar) Copyright notice © CRC for Catchment Hydrology, Australia 2005 Legal Information To the extent permitted by law, the CRC for Catchment Hydrology (including its employees and consultants) accepts no responsibility and excludes all liability whatsoever in respect of any person's use or reliance on this publication or any part of it. Acknowledgements TREND is a product from the CRC for Catchment Hydrology’s (CRCCH) Climate Variability Program. The scientific development and testing were carried out by Francis Chiew1 and Lionel Siriwardena1 and the software was developed by Sylvain Arene2 and Joel Rahman3. The Product Manager of TREND is Francis Chiew. 1 University of Melbourne 2 University of Melbourne and Griffith University 3 CSIRO Land and Water TREND – User Guide CONTENTS 1 Introduction...........................................................1 1.1 The user guide.............................................................................................. 1 1.2 TREND......................................................................................................... 1 1.2.1 Overview.................................................................................... 1 1.2.2 Features ..................................................................................... 2 1.2.3 Audience .................................................................................... 2 1.2.4 Limitations and cautionary notes.................................................... 2 1.3 Related documents........................................................................................ 2 1.4 Data requirements......................................................................................... 3 1.4.1 Input data................................................................................... 3 1.4.2 Calculated results ........................................................................ 3 1.5 References and training.................................................................................. 3 2 Installation ............................................................4 2.1 Technical specifications.................................................................................. 4 2.2 Licence agreement ........................................................................................ 4 2.3 Folders ........................................................................................................ 5 2.4 Installation ................................................................................................... 5 2.4.1 Framework installation ................................................................. 5 2.4.2 Stand-alone PC........................................................................... 5 2.5 Uninstalling TREND....................................................................................... 6 3 Using TREND.........................................................7 3.1 Getting started.............................................................................................. 7 3.2 Data Input screen.......................................................................................... 7 3.3 Options screen ............................................................................................. 9 3.3.1 Test selection panel...................................................................... 9 3.3.2 Resampling panel ........................................................................ 9 3.3.3 Period panel ............................................................................... 9 3.3.4 Display panel ............................................................................ 10 3.3.5 Running the tests........................................................................ 10 3.4 Results screen ............................................................................................. 10 3.4.1 Test display panel ...................................................................... 10 3.4.2 Summary statistics panel..............................................................10 3.4.3 Test result panel .........................................................................10 3.5 Saving test results.........................................................................................12 4 Description of statistical tests ...............................14 4.1 Statistical testing ..........................................................................................14 4.1.1 Basic concepts ...........................................................................14 4.1.2 Significance level........................................................................15 4.1.3 Resampling analysis to estimate significance level...........................15 4.1.4 Parametric and non-parametric tests.............................................15 4.2 Description of statistical tests in TREND...........................................................16 4.2.1 Mann-Kendall Test......................................................................16 4.2.2 Spearman’s Rho Test...................................................................17 4.2.3 Linear Regression Test.................................................................17 4.2.4 Distribution Free CUSUM Test......................................................18 4.2.5 Cumulative Deviation Test ...........................................................18 4.2.6 Worsley Likelihood Ratio Test.......................................................19 4.2.7 Rank-Sum Test ...........................................................................20 4.2.8 Student’s t Test ...........................................................................20 4.2.9 Median Crossing Test..................................................................21 4.2.10 Turning Points Test......................................................................21 4.2.11 Rank Difference Test ...................................................................21 4.2.12 Autocorrelation Test....................................................................22 5 References...........................................................23 Introduction 1 1 Introduction TREND is designed to facilitate statistical testing for trend, change and randomness in hydrological and other time series data. TREND has 12 statistical tests, based on the WMO/UNESCO Expert Workshop on Trend/Change Detection and on the CRC for Catchment Hydrology publication Hydrological Recipes. 1.1 The user guide The User Guide provides basic instructions for using TREND. It also provides an overview of statistical testing and descriptions of the 12 statistical tests in TREND. 1.2 TREND 1.2.1 Overview TREND has 12 statistical tests that can be used to test for trend, change and randomness in hydrological and other time series data: • Mann-Kendall (non-parametric test for trend) • Spearman’s Rho (non-parametric test for trend) • Linear Regression (parametric test for trend) • Distribution-Free CUSUM (non-parametric test for step jump in mean) • Cumulative Deviation (parametric test for step jump in mean) • Worsley Likelihood Ratio (parametric test for step jump in mean) • Rank-Sum (non-parametric test for difference in median from two data periods) • Student’s t (parametric test for difference in mean from two data periods) • Median Crossing (non-parametric test for randomness) • Turning Points (non-parametric test for randomness) • Rank Difference (non-parametric test for randomness) • Autocorrelation (parametric test for randomness). Trend User Guide 2 1.2.2 Features • TREND allows easy statistical testing using different tests • TREND supports various time series data input formats • TREND provides simple statement of test result • TREND displays test statistic and critical values for various statistical significance levels • TREND performs resampling analysis to determine critical test statistic values • TREND allows easy retrieval of test results. 1.2.3 Audience TREND is designed for hydrologists, environmental scientists, consultants and researchers to facilitate statistical testing for trend, change and randomness in time series data. 1.2.4 Limitations and cautionary notes TREND performs the statistical tests only on annual time series data (see Section 3.2 on how you can modify the data file to use TREND for non-annual time series data). The statistical tests in TREND are only valid if the time series data is not serially correlated. Most (but not all) time-series data with time steps shorter than the annual time step are serially correlated. The Autocorrelation test (one of the tests in TREND) can be used to test if the time series data is serially correlated. Users are strongly encouraged to carry out an exploratory data analysis (EDA) before using TREND. EDA involves using graphs to explore, understand and present data. EDA allows much greater appreciation of the features in the data than summary statistics or statistical significance level. Outliers and obvious errors in the data can also be detected through EDA. A well-conducted EDA may eliminate the need for a formal statistical analysis. At the very least, the user should view a time series plot of the data (with a trend line fitted to the data) before using TREND. Users should have a good understanding of the statistical tests and assumptions (read Chapter 4). Users should also note that a statistical test provides evidence, not proof (if a trend/change is detected, the reason for the trend/change must be investigated). Statistical significance is not the same as importance (e.g., a change may be detected, but the size of the change may be so small that it is of little importance). 1.3 Related documents TrendTests.xls The statistical tests in TREND are relatively easy to understand and the user can gain a good appreciation of the tests by following the descriptions in Chapter 4 and the examples in the Excel spreadsheet TrendTests.xls. TrendTests.xls can be downloaded from Documentation in the TREND homepage (www.toolkit.net.au/trend). TrendWorkshop.ppt TrendWorkshop.ppt is a powerpoint presentation used for the CRC for Catchment Hydrology Modelling School. It presents an overview of the need for analysing data for trend/change, exploratory data analysis, basic concepts in statistical testing and types of statistical tests. Introduction 3 TrendWorkshop.ppt can be downloaded from Documentation in the TREND homepage (www.toolkit.net.au/trend). 1.4 Data requirements 1.4.1 Input data TREND requires a continuous time series as input data. Various standard TIME/toolkit time series data formats are supported by TREND. TREND performs the statistical tests on annual time series data (i.e., TREND will convert daily and monthly time series data into an annual time series before carrying out the statistical testing on the annual time series - see Section 3.2 on how you can modify the data file to use TREND for non-annual time series data). 1.4.2 Calculated results TREND displays as an output the value of the test statistic, the critical values of the test statistic at α = 0.01, α = 0.05 and α = 0.1 significance levels, and a statement of the test result, for all the statistical tests selected by the user. 1.5 References and training TREND is a product developed by the CRC for Catchment Hydrology (CRCCH). As a part of product delivery, the CRCCH runs training workshops. Details of workshops are posted on the Toolkit website (www.toolkit.net.au) in the news and events sections. The main references for TREND are: Kundzewicz, Z.W. and Robson, A. (Editors) (2000) Detecting Trend and Other Changes in Hydrological Data. World Climate Program – Water, WMO/UNESCO, WCDMP- 45, WMO/TD 1013, Geneva, 157 pp. Grayson, R.B., Argent, R.M., Nathan, R.J., McMahon, T.A. and Mein, R. (1996) Hydrological Recipes: Estimation Techniques in Australian Hydrology. Cooperative Research Centre for Catchment Hydrology, Australia, 125 pp. Trend User Guide 4 2 Installation 2.1 Technical specifications Type of Machine Intel based PC with CD-ROM drive Processor Minimum: 133 MHz Pentium class processor Recommended: 400 MHz or faster (particularly when resampling analysis is used) Memory Minimum: 128 MB of RAM Recommended: 512 MB Disk Space Little (< 100 MB) Operating System Windows 2000 Windows XP Professional Windows NT®4.0 + Service Pack 6a Windows® Server 2003 Other Supporting Software To run TREND, you will also need (see Section 2.4.1 on how you can install these): - .NET Framework 1.1 Redistributable or later; and - Visual J#.NET Redistributable Package 1.1 The person installing the software must have local administrator access on the computer. Ideally, you should also have the relevant permissions to install and uninstall software. Note If you are using a networked computer, then inform your system administrator before applying any service packs or updates, as there may be other applications on your computer that could be affected by these updates. 2.2 Licence agreement A uploads/Litterature/ trend-user-guide.pdf