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https://issues.apache.org/jira/browse/STATISTICS-62?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17686180#comment-17686180
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Gilles Sadowski commented on STATISTICS-62:
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* Wrt the "cost" of object creation: Do we still (in recent JVMs) need to worry
about it (for such small instances)?
* Are we sure that any present or future implementation of a test is immutable?
If not, won't it complicate the API that the default behaviour is to use a
singleton (e.g. when the instance could be accessed from multiple threads)?
* Wrt "overengineering": IIUC, it's a trade-off (a single "complex" builder
class that can easily accommodate new options vs each test class having to
maintain its options handling), with small impact on the API (only having to
call "get").
> Port o.a.c.math.stat.inference to a commons-statistics-inference module
> -----------------------------------------------------------------------
>
> Key: STATISTICS-62
> URL: https://issues.apache.org/jira/browse/STATISTICS-62
> Project: Commons Statistics
> Issue Type: New Feature
> Components: inference
> Affects Versions: 1.0
> Reporter: Alex Herbert
> Priority: Major
>
> The o.a.c.math4.legacy.stat.inference package contains:
>
> {noformat}
> AlternativeHypothesis.java
> BinomialTest.java
> ChiSquareTest.java
> GTest.java
> InferenceTestUtils.java
> KolmogorovSmirnovTest.java
> MannWhitneyUTest.java
> OneWayAnova.java
> TTest.java
> WilcoxonSignedRankTest.java{noformat}
> The are few dependencies on other math packages. The notable exceptions are:
>
> 1. KolmogorovSmirnovTest which requires matrix support. This is for
> multiplication of a square matrix to support a matrix power function. This
> uses a double matrix and the same code is duplicated for a BigFraction
> matrix. Such code can be ported internally to support only the required
> functions. It can also drop the defensive copy strategy used by Commons Math
> in matrices to allow multiply in-place where appropriate for performance
> gains.
> 2. OneWayAnova which collates the sum, sum of squares and count using
> SummaryStatistics. This can be done using an internal class. It is possible
> to call the test method using already computed SummaryStatistics. The method
> that does this using the SummaryStatistics as part of the API can be dropped,
> or supported using an interface that returns: getSum, getSumOfSquares, getN.
> All the inference Test classes have instance methods but no state. The
> InferenceTestUtils is a static class that holds references to a singleton for
> each class and provides static methods to pass through the underlying
> instances.
> I suggest changing the test classes to have only static methods and dropping
> InferenceTestUtils.
>
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