Seasonal Kendall Test for Trend US Geological Survey, 2005 Data set: Example SKL1a - Seasonal Kendall with LOWESS, input type 1 The record is 12 complete water years with 12 seasons per year beginning in water year 1974. Flow-adjusted concentrations were calculated as residuals from a LOWESS smooth line (f = 0.50) for concentration vs. streamflow The tau correlation coefficient is -0.176 S = -42. z = -1.808 p = 0.0705 p = 0.1985 adjusted for correlation among seasons (such as serial dependence) The adjusted p-value should be used only for data with more than 10 annual values per season. The estimated trend may be described by the equation: Residual = 0.000 + -3.761 * Time where Time = Year (as a decimal) - 1973.75 (beginning of first water year)