psteitz 2004/02/29 13:25:09
Modified: math/xdocs/userguide index.xml stat.xml
Log:
Added more content to statistics and distributions user guide.
Revision Changes Path
1.7 +2 -2 jakarta-commons/math/xdocs/userguide/index.xml
Index: index.xml
===================================================================
RCS file: /home/cvs/jakarta-commons/math/xdocs/userguide/index.xml,v
retrieving revision 1.6
retrieving revision 1.7
diff -u -r1.6 -r1.7
--- index.xml 29 Feb 2004 18:50:10 -0000 1.6
+++ index.xml 29 Feb 2004 21:25:08 -0000 1.7
@@ -36,7 +36,7 @@
<li><a href="overview.html#dependencies">0.5 Dependencies</a></li>
</ul></li>
- <li><a href="stat.html">1. Statistics</a>
+ <li><a href="stat.html">1. Statistics and Distributions</a>
<ul>
<li><a href="stat.html#overview">1.1 Overview</a></li>
<li><a href="stat.html#univariate">1.2 Univariate
statistics</a></li>
1.9 +63 -6 jakarta-commons/math/xdocs/userguide/stat.xml
Index: stat.xml
===================================================================
RCS file: /home/cvs/jakarta-commons/math/xdocs/userguide/stat.xml,v
retrieving revision 1.8
retrieving revision 1.9
diff -u -r1.8 -r1.9
--- stat.xml 29 Feb 2004 18:50:10 -0000 1.8
+++ stat.xml 29 Feb 2004 21:25:08 -0000 1.9
@@ -23,14 +23,70 @@
<title>The Commons Math User Guide - Statistics</title>
</properties>
<body>
- <section name="1 Statistics">
+ <section name="1 Statistics and Distributions">
<subsection name="1.1 Overview" href="overview">
- <p>This is yet to be written. Any contributions will be greatfully
- accepted!</p>
+ <p>
+ The statistics and distributions packages provide frameworks and
implementations for
+ basic univariate statistics, frequency distributions, bivariate
regression, t- and chi-square test
+ statistics and some commonly used probability distributions.
+ </p>
</subsection>
<subsection name="1.2 Univariate statistics" href="univariate">
- <p>This is yet to be written. Any contributions will be gratefully
- accepted!</p>
+ <p>
+ The stat package includes a framework and default implementations for the
following univariate
+ statistics:
+ <ul>
+ <li>arithmetic and geometric means</li>
+ <li>variance and standard deviation</li>
+ <li>sum, product, log sum, sum of squared values</li>
+ <li>minimum, maximum, median, and percentiles</li>
+ <li>skewness and kurtosis</li>
+ <li>first, second, third and fourth moments</li>
+ </ul>
+ </p>
+ <p>
+ With the exception of percentiles and the median, all of these statistics
can be computed without
+ maintaining the full list of input data values in memory. The stat
package provides interfaces and
+ implementations that do not require value storage as well as
implementations that operate on arrays
+ of stored values.
+ </p>
+ <p>
+ The top level interface is
+ <a
href="../apidocs/org/apache/commons/math/stat/univariate/UnivariateStatistic.html">
+ org.apache.commons.math.stat.univariate.UnivariateStatistic.</a> This
interface, implemented by
+ all statistics, consists of <code>evaluate()</code> methods that take
double[] arrays as arguments and return
+ the value of the statistic. This interface is extended by
+ <a
href="../apidocs/org/apache/commons/math/stat/univariate/StorelessUnivariateStatistic.html">
+ org.apache.commons.math.stat.univariate.StorelessUnivariateStatistic,</a>
which adds <code>increment(),</code>
+ <code>getResult()</code> and associated methods to support "storageless"
implementations that
+ maintain counters, sums or other state information as values are added
using the <code>increment()</code>
+ method.
+ </p>
+ <p>
+ Abstract implementations of the top level interfaces are provided in
+ <a
href="../apidocs/org/apache/commons/math/stat/univariate/AbstractUnivariateStatistic.html">
+ org.apache.commons.math.stat.univariate.AbstractUnivariateStatistic</a>
and
+ <a
href="../apidocs/org/apache/commons/math/stat/univariate/AbstractStorelessUnivariateStatistic.html">
+
org.apache.commons.math.stat.univariate.AbstractStorelessUnivariateStatistic</a>
respectively.
+ </p>
+ <p>
+ Each statistic is implemented as a separate class, in one of the
subpackages (moment, rank, summary) and
+ each extends one of the abstract classes above (depending on whether or
not value storage is required to
+ compute the statistic).
+ There are several ways to instantiate and use statistics. Statistics can
be instantiated and used directly, but it is
+ generally more convenient to access them using the provided aggregates:
+ <table>
+ <tr><th>Aggregate</th><th>Statistics Included</th><th>Values
stored?</th></tr>
+ <tr><td><a
href="../apidocs/org/apache/commons/math/stat/DescriptiveStatistics.html">
+
org.apache.commons.math.stat.DescriptiveStatistics</a></td><td>All</td><td>Yes</td></tr>
+ <tr><td><a
href="../apidocs/org/apache/commons/math/stat/SummaryStatistics.html">
+ org.apache.commons.math.stat.SummaryStatistics</a></td><td>min, max,
mean, geometric mean, n, sum, sum of squares, standard deviation,
variance</td><td>No</td></tr>
+ </table>
+ TODO: add code sample
+ There is also a utility class, <a
href="../apidocs/org/apache/commons/math/stat/StatUtils.html">
+ org.apache.commons.math.stat.StatUtils,</a> that provides static methods
for computing statistics
+ from double[] arrays.
+ </p>
</subsection>
<subsection name="1.3 Frequency distributions" href="frequency">
<p>This is yet to be written. Any contributions will be gratefully
@@ -73,6 +129,7 @@
<tr><td>F</td><td>createFDistribution</td><td><div>Numerator degrees of
freedom</div><div>Denominator degrees of freedom</div></td></tr>
<tr><td>Gamma</td><td>createGammaDistribution</td><td><div>Alpha</div><div>Beta</div></td></tr>
<tr><td>Hypergeometric</td><td>createHypogeometricDistribution</td><td><div>Population
size</div><div>Number of successes in population</div><div>Sample size</div></td></tr>
+ <tr><td>Normal
(Gaussian)</td><td>createNormalDistribution</td><td><div>Mean</div><div>Standard
Deviation</div></td></tr>
<tr><td>t</td><td>createTDistribution</td><td><div>Degrees of
freedom</div></td></tr>
</table>
</p>
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