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<meta property="og:description" content="Calculates a nonparametric statistic for a monotonic trend 
             based on the Kendall tau statistic and the Theil-Sen slope 
             modification" />




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    <h1>Kendall tau trend with continuity correction for raster time-series</h1>
    <small class="dont-index">Source: <a href='https://github.com/jeffreyevans/spatialEco/blob/master/R/raster.kendall.R'><code>R/raster.kendall.R</code></a></small>
    <div class="hidden name"><code>raster.kendall.Rd</code></div>
    </div>

    <div class="ref-description">
    <p>Calculates a nonparametric statistic for a monotonic trend 
             based on the Kendall tau statistic and the Theil-Sen slope 
             modification</p>
    </div>

    <pre class="usage"><span class='fu'>raster.kendall</span><span class='op'>(</span>
  <span class='va'>x</span>,
  intercept <span class='op'>=</span> <span class='cn'>FALSE</span>,
  p.value <span class='op'>=</span> <span class='cn'>FALSE</span>,
  z.value <span class='op'>=</span> <span class='cn'>FALSE</span>,
  confidence <span class='op'>=</span> <span class='cn'>FALSE</span>,
  tau <span class='op'>=</span> <span class='cn'>FALSE</span>,
  <span class='va'>...</span>
<span class='op'>)</span></pre>

    <h2 class="hasAnchor" id="arguments"><a class="anchor" href="#arguments"></a>Arguments</h2>
    <table class="ref-arguments">
    <colgroup><col class="name" /><col class="desc" /></colgroup>
    <tr>
      <th>x</th>
      <td><p>A rasterStack object with at least 5 layers</p></td>
    </tr>
    <tr>
      <th>intercept</th>
      <td><p>(FALSE/TRUE) return a raster with the pixel 
wise intercept values</p></td>
    </tr>
    <tr>
      <th>p.value</th>
      <td><p>(FALSE/TRUE) return a raster with the pixel 
wise p.values</p></td>
    </tr>
    <tr>
      <th>z.value</th>
      <td><p>(FALSE/TRUE) return a raster with the pixel 
wise z.values</p></td>
    </tr>
    <tr>
      <th>confidence</th>
      <td><p>(FALSE/TRUE) return a raster with the pixel 
wise 95 pct confidence levels</p></td>
    </tr>
    <tr>
      <th>tau</th>
      <td><p>(FALSE/TRUE) return a raster with the pixel wise 
tau correlation values</p></td>
    </tr>
    <tr>
      <th>...</th>
      <td><p>Additional arguments passed to the raster 
overlay function</p></td>
    </tr>
    </table>

    <h2 class="hasAnchor" id="value"><a class="anchor" href="#value"></a>Value</h2>

    <p>Depending on arguments, a raster layer or rasterBrick object containing:</p><ul>
<li><p>raster layer 1 slope for trend, always returned</p></li>
<li><p>raster layer 2 intercept for trend if intercept TRUE</p></li>
<li><p>raster layer 3 p value for trend fit if p.value TRUE</p></li>
<li><p>raster layer 4 z value for trend fit if z.value TRUE</p></li>
<li><p>raster layer 5 lower confidence level at 95 pct, if 
                          confidence TRUE</p></li>
<li><p>raster layer 6 upper confidence level at 95 pct, if 
                          confidence TRUE</p></li>
<li><p>raster layer 7 Kendall's tau two-sided test, reject null at 0, 
                          if tau TRUE</p></li>
</ul>

    <h2 class="hasAnchor" id="details"><a class="anchor" href="#details"></a>Details</h2>

    <p>This function implements Kendall's nonparametric test for a monotonic trend 
using the Theil-Sen (Theil 1950; Sen 1968; Siegel 1982) method to estimate 
the slope and related confidence intervals.</p>
    <h2 class="hasAnchor" id="references"><a class="anchor" href="#references"></a>References</h2>

    <p>Theil, H. (1950) A rank invariant method for linear and polynomial regression 
  analysis.  Nederl. Akad. Wetensch. Proc. Ser. A 53:386-392 (Part I), 
  53:521-525 (Part II), 53:1397-1412 (Part III).</p>
<p>Sen, P.K. (1968) Estimates of Regression Coefficient Based on Kendall's tau. 
  Journal of the American Statistical Association. 63(324):1379-1389.</p>
<p>Siegel, A.F. (1982) Robust Regression Using Repeated Medians. 
  Biometrika, 69(1):242-244</p>
    <h2 class="hasAnchor" id="see-also"><a class="anchor" href="#see-also"></a>See also</h2>

    <div class='dont-index'><p><code><a href='https://rdrr.io/pkg/EnvStats/man/kendallTrendTest.html'>kendallTrendTest</a></code> for model details</p>
<p><code><a href='https://rdrr.io/pkg/raster/man/overlay.html'>overlay</a></code> for available ... arguments</p></div>
    <h2 class="hasAnchor" id="author"><a class="anchor" href="#author"></a>Author</h2>

    <p>Jeffrey S. Evans  &lt;jeffrey_evans@tnc.org&gt;</p>

    <h2 class="hasAnchor" id="examples"><a class="anchor" href="#examples"></a>Examples</h2>
    <pre class="examples"><div class='input'><span class='co'># \donttest{</span>
 <span class='kw'><a href='https://rdrr.io/r/base/library.html'>library</a></span><span class='op'>(</span><span class='va'><a href='https://rspatial.org/raster'>raster</a></span><span class='op'>)</span>
 <span class='va'>r.logo</span> <span class='op'>&lt;-</span> <span class='fu'><a href='https://rdrr.io/pkg/raster/man/stack.html'>stack</a></span><span class='op'>(</span><span class='fu'><a href='https://rdrr.io/r/base/system.file.html'>system.file</a></span><span class='op'>(</span><span class='st'>"external/rlogo.grd"</span>, package<span class='op'>=</span><span class='st'>"raster"</span><span class='op'>)</span>,
                 <span class='fu'><a href='https://rdrr.io/r/base/system.file.html'>system.file</a></span><span class='op'>(</span><span class='st'>"external/rlogo.grd"</span>, package<span class='op'>=</span><span class='st'>"raster"</span><span class='op'>)</span>,
           <span class='fu'><a href='https://rdrr.io/r/base/system.file.html'>system.file</a></span><span class='op'>(</span><span class='st'>"external/rlogo.grd"</span>, package<span class='op'>=</span><span class='st'>"raster"</span><span class='op'>)</span><span class='op'>)</span> 
 
 <span class='co'># Calculate trend slope with p-value and confidence level(s)</span>
 <span class='co'># ("slope","intercept", "p.value","z.value", "LCI","UCI","tau")</span>
   <span class='va'>k</span> <span class='op'>&lt;-</span> <span class='fu'>raster.kendall</span><span class='op'>(</span><span class='va'>r.logo</span>, p.value<span class='op'>=</span><span class='cn'>TRUE</span>, z.value<span class='op'>=</span><span class='cn'>TRUE</span>, 
                       intercept<span class='op'>=</span><span class='cn'>TRUE</span>, confidence<span class='op'>=</span><span class='cn'>TRUE</span>, 
                       tau<span class='op'>=</span><span class='cn'>TRUE</span><span class='op'>)</span>
     <span class='fu'><a href='https://rdrr.io/pkg/raster/man/plot.html'>plot</a></span><span class='op'>(</span><span class='va'>k</span><span class='op'>)</span>
</div><div class='img'><img src='raster.kendall-1.png' alt='' width='700' height='433' /></div><div class='input'><span class='co'># }</span>

</div></pre>
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