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Scientific Investigations Report 2005–5275

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Computer Program for the Kendall Family of Trend Tests

By Dennis R. Helsel, David K. Mueller, and James R. Slack

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SIR 5275
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The Seasonal Kendall (SK) test for trend was developed by the U.S. Geological Survey and has become the most frequently used test for trend in the environmental sciences. Recently the test was modified to form the Regional Kendall (RK) test for trend. In this form, trends at numerous locations within a region are tested to determine whether the direction of trend is consistent across the entire region. Computer code developed at the USGS in the 1980s to perform the SK test is no longer widely available. Other versions written by other scientists may or may not be easily available, and may require commercial software in order to be run. These other versions do not explicitly compute the RK test. Therefore, the original code for computing the SK test has been repackaged into a program that runs under the Windows operating system. This program may be used to verify that other implementations of the test give the same results as the original. The program also provides a means for computing the RK test and the simpler Mann-Kendall test for trend.

Version 1.0

Posted June 2006

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    (This version of the report is accessible as defined in Section 508 of the Rehabilitation Act of 1973, Amendments of 1998.)
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