<div dir="ltr"><div dir="ltr"><a href="http://www.ncl.ucar.edu/Document/Functions/Built-in/betainc.shtml"><b>http://www.ncl.ucar.edu/Document/Functions/Built-in/betainc.shtml</b></a></div><div dir="ltr"><br></div><div>See Example 2</div><div><pre>  df   = 20 
  tval = 2.08  <br>  prob = <strong>betainc</strong>( df/(df+tval^2), df/2.0, 0.5)<br></pre><pre>So: x = df/(df+tval^2)<br>    a = df/2.0<br>    b = 0.5<br><br></pre><pre>As noted in the "Description" section.<br></pre><pre>This returns the same results as in the "Numerical Recipes" text.<br><br></pre><pre>Good luck<br></pre></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Apr 25, 2019 at 11:48 PM Dr. Alvarinho J. Luis <<a href="mailto:alvluis1@gmail.com">alvluis1@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-size:large">
<div class="gmail_default" style="font-size:large">Dear all,</div><div class="gmail_default" style="font-size:large"><br></div><div class="gmail_default" style="font-size:large">  I am struggling on how to use<b> betainc </b>function
 to compute significance (or  probability) at p<0.05 (95% 
probability) using three dimensional variable:  I have sea ice 
concentration fields for 23 years .  I would like to 
compute the significance of the sea ice concentration trend using 
betainc... <br></div><div class="gmail_default" style="font-size:large"><br></div><div class="gmail_default" style="font-size:large">for df=23-2=21</div><div class="gmail_default" style="font-size:large">student t statistic at 95% with two tailed test= 2.069</div><div class="gmail_default" style="font-size:large">
<pre>prob = (1.-<b>betainc</b>(x,a,b))*100. </pre>

</div><div class="gmail_default" style="font-size:large">what is x, a and b ?</div><div class="gmail_default" style="font-size:large"><br></div><div class="gmail_default" style="font-size:large">how to obtain 95% probability ?<br></div><div class="gmail_default" style="font-size:large">I am struggling to implement this function for three dimensional (x,y,t) fields<br></div><div class="gmail_default" style="font-size:large">Please help.</div><div class="gmail_default" style="font-size:large"><br></div><div class="gmail_default" style="font-size:large"><br></div><div class="gmail_default" style="font-size:large">Thanks & regards,</div><div class="gmail_default" style="font-size:large">Luis</div>

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