Author: gregs
Date: Sat Sep 10 05:20:56 2011
New Revision: 1167460
URL: http://svn.apache.org/viewvc?rev=1167460&view=rev
Log:
Changing doc to reflect revised constructor for SimpleRegression
Modified:
commons/proper/math/trunk/src/site/xdoc/userguide/stat.xml
Modified: commons/proper/math/trunk/src/site/xdoc/userguide/stat.xml
URL:
http://svn.apache.org/viewvc/commons/proper/math/trunk/src/site/xdoc/userguide/stat.xml?rev=1167460&r1=1167459&r2=1167460&view=diff
==============================================================================
--- commons/proper/math/trunk/src/site/xdoc/userguide/stat.xml (original)
+++ commons/proper/math/trunk/src/site/xdoc/userguide/stat.xml Sat Sep 10
05:20:56 2011
@@ -365,6 +365,10 @@ System.out.println(f.getCumPct("z")); /
<code> y = intercept + slope * x </code>
</p>
<p>
+ or
+ <p>
+ <code> y = slope * x </code>
+ </p>
Standard errors for <code>intercept</code> and <code>slope</code>
are
available as well as ANOVA, r-square and Pearson's r statistics.
</p>
@@ -408,7 +412,6 @@ System.out.println(f.getCumPct("z")); /
Here are some examples.
<dl>
<dt>Estimate a model based on observations added one at a time</dt>
- <br></br>
<dd>Instantiate a regression instance and add data points
<source>
regression = new SimpleRegression();
@@ -445,8 +448,8 @@ System.out.println(regression.predict(1.
More data points can be added and subsequent getXxx calls will
incorporate
additional data in statistics.
</dd>
+ <br></br>
<dt>Estimate a model from a double[][] array of data points</dt>
- <br></br>
<dd>Instantiate a regression object and load dataset
<source>
double[][] data = { { 1, 3 }, {2, 5 }, {3, 7 }, {4, 14 }, {5, 11 }};
@@ -468,6 +471,34 @@ System.out.println(regression.getSlopeSt
More data points -- even another double[][] array -- can be added and
subsequent
getXxx calls will incorporate additional data in statistics.
</dd>
+<br></br>
+ <dt>Estimate a model from a double[][] array of data points,
<em>excluding</em> the intercept</dt>
+ <dd>Instantiate a regression object and load dataset
+ <source>
+double[][] data = { { 1, 3 }, {2, 5 }, {3, 7 }, {4, 14 }, {5, 11 }};
+SimpleRegression regression = new SimpleRegression(false);
+//the argument, false, tells the class not to include a constant
+regression.addData(data);
+ </source>
+ </dd>
+ <dd>Estimate regression model based on data
+ <source>
+System.out.println(regression.getIntercept());
+// displays intercept of regression line, since we have constrained the
constant, 0.0 is returned
+
+System.out.println(regression.getSlope());
+// displays slope of regression line
+
+System.out.println(regression.getSlopeStdErr());
+// displays slope standard error
+
+System.out.println(regression.getInterceptStdErr() );
+// will return Double.NaN, since we constrained the parameter to zero
+ </source>
+ Caution must be exercised when interpreting the slope when no
constant is being estimated. The slope
+ may be biased.
+ </dd>
+
</dl>
</p>
</subsection>
