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Java > Open Source Codes > org > apache > commons > math > stat > inference > ChiSquareTestTest


1 /*
2  * Copyright 2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 package org.apache.commons.math.stat.inference;
17
18 import junit.framework.Test;
19 import junit.framework.TestCase;
20 import junit.framework.TestSuite;
21
22 /**
23  * Test cases for the ChiSquareTestImpl class.
24  *
25  * @version $Revision$ $Date: 2005-06-04 20:58:14 -0700 (Sat, 04 Jun 2005) $
26  */
27
28 public class ChiSquareTestTest extends TestCase {
29
30     protected ChiSquareTest testStatistic = new ChiSquareTestImpl();
31
32     public ChiSquareTestTest(String JavaDoc name) {
33         super(name);
34     }
35
36     public void setUp() {
37     }
38
39     public static Test suite() {
40         TestSuite suite = new TestSuite(ChiSquareTestTest.class);
41         suite.setName("TestStatistic Tests");
42         return suite;
43     }
44
45     public void testChiSquare() throws Exception JavaDoc {
46  
47         // Target values computed using R version 1.8.1
48 // Some assembly required ;-)
49 // Use sum((obs - exp)^2/exp) for the chi-square statistic and
50 // 1 - pchisq(sum((obs - exp)^2/exp), length(obs) - 1) for the p-value
51
52         long[] observed = {10, 9, 11};
53         double[] expected = {10, 10, 10};
54         assertEquals("chi-square statistic", 0.2, testStatistic.chiSquare(expected, observed), 10E-12);
55         assertEquals("chi-square p-value", 0.904837418036, testStatistic.chiSquareTest(expected, observed), 1E-10);
56         
57         long[] observed1 = { 500, 623, 72, 70, 31 };
58         double[] expected1 = { 485, 541, 82, 61, 37 };
59         assertEquals( "chi-square test statistic", 16.4131070362, testStatistic.chiSquare(expected1, observed1), 1E-10);
60         assertEquals("chi-square p-value", 0.002512096, testStatistic.chiSquareTest(expected1, observed1), 1E-9);
61         assertTrue("chi-square test reject", testStatistic.chiSquareTest(expected1, observed1, 0.003));
62         assertTrue("chi-square test accept", !testStatistic.chiSquareTest(expected1, observed1, 0.002));
63
64         try {
65             testStatistic.chiSquareTest(expected1, observed1, 95);
66             fail("alpha out of range, IllegalArgumentException expected");
67         } catch (IllegalArgumentException JavaDoc ex) {
68             // expected
69 }
70         
71         long[] tooShortObs = { 0 };
72         double[] tooShortEx = { 1 };
73         try {
74             testStatistic.chiSquare(tooShortEx, tooShortObs);
75             fail("arguments too short, IllegalArgumentException expected");
76         } catch (IllegalArgumentException JavaDoc ex) {
77             // expected
78 }
79
80         // unmatched arrays
81 long[] unMatchedObs = { 0, 1, 2, 3 };
82         double[] unMatchedEx = { 1, 1, 2 };
83         try {
84             testStatistic.chiSquare(unMatchedEx, unMatchedObs);
85             fail("arrays have different lengths, IllegalArgumentException expected");
86         } catch (IllegalArgumentException JavaDoc ex) {
87             // expected
88 }
89         
90         // 0 expected count
91 expected[0] = 0;
92         try {
93             testStatistic.chiSquareTest(expected, observed, .01);
94             fail("bad expected count, IllegalArgumentException expected");
95         } catch (IllegalArgumentException JavaDoc ex) {
96             // expected
97 }
98         
99         // negative observed count
100 expected[0] = 1;
101         observed[0] = -1;
102         try {
103             testStatistic.chiSquareTest(expected, observed, .01);
104             fail("bad expected count, IllegalArgumentException expected");
105         } catch (IllegalArgumentException JavaDoc ex) {
106             // expected
107 }
108         
109     }
110
111     public void testChiSquareIndependence() throws Exception JavaDoc {
112         
113         // Target values computed using R version 1.8.1
114
115         long[][] counts = { {40, 22, 43}, {91, 21, 28}, {60, 10, 22}};
116         assertEquals( "chi-square test statistic", 22.709027688, testStatistic.chiSquare(counts), 1E-9);
117         assertEquals("chi-square p-value", 0.000144751460134, testStatistic.chiSquareTest(counts), 1E-9);
118         assertTrue("chi-square test reject", testStatistic.chiSquareTest(counts, 0.0002));
119         assertTrue("chi-square test accept", !testStatistic.chiSquareTest(counts, 0.0001));
120         
121         long[][] counts2 = {{10, 15}, {30, 40}, {60, 90} };
122         assertEquals( "chi-square test statistic", 0.168965517241, testStatistic.chiSquare(counts2), 1E-9);
123         assertEquals("chi-square p-value",0.918987499852, testStatistic.chiSquareTest(counts2), 1E-9);
124         assertTrue("chi-square test accept", !testStatistic.chiSquareTest(counts2, 0.1));
125         
126         // ragged input array
127 long[][] counts3 = { {40, 22, 43}, {91, 21, 28}, {60, 10}};
128         try {
129             testStatistic.chiSquare(counts3);
130             fail("Expecting IllegalArgumentException");
131         } catch (IllegalArgumentException JavaDoc ex) {
132             // expected
133 }
134         
135         // insufficient data
136 long[][] counts4 = {{40, 22, 43}};
137         try {
138             testStatistic.chiSquare(counts4);
139             fail("Expecting IllegalArgumentException");
140         } catch (IllegalArgumentException JavaDoc ex) {
141             // expected
142 }
143         long[][] counts5 = {{40}, {40}, {30}, {10}};
144         try {
145             testStatistic.chiSquare(counts5);
146             fail("Expecting IllegalArgumentException");
147         } catch (IllegalArgumentException JavaDoc ex) {
148             // expected
149 }
150         
151         // negative counts
152 long[][] counts6 = {{10, -2}, {30, 40}, {60, 90} };
153         try {
154             testStatistic.chiSquare(counts6);
155             fail("Expecting IllegalArgumentException");
156         } catch (IllegalArgumentException JavaDoc ex) {
157             // expected
158 }
159         
160         // bad alpha
161 try {
162             testStatistic.chiSquareTest(counts, 0);
163             fail("Expecting IllegalArgumentException");
164         } catch (IllegalArgumentException JavaDoc ex) {
165             // expected
166 }
167     }
168     
169     public void testChiSquareLargeTestStatistic() throws Exception JavaDoc {
170         double[] exp = new double[] {
171             3389119.5, 649136.6, 285745.4, 25357364.76, 11291189.78, 543628.0,
172             232921.0, 437665.75
173         };
174
175         long[] obs = new long[] {
176             2372383, 584222, 257170, 17750155, 7903832, 489265, 209628, 393899
177         };
178         org.apache.commons.math.stat.inference.ChiSquareTestImpl csti =
179             new org.apache.commons.math.stat.inference.ChiSquareTestImpl();
180         double cst = csti.chiSquareTest(exp, obs);
181         assertEquals("chi-square p-value", 0.0, cst, 1E-3);
182         assertEquals( "chi-square test statistic",
183                 3624883.342907764, testStatistic.chiSquare(exp, obs), 1E-9);
184     }
185     
186     /** Contingency table containing zeros - PR # 32531 */
187     public void testChiSquareZeroCount() throws Exception JavaDoc {
188         // Target values computed using R version 1.8.1
189 long[][] counts = { {40, 0, 4}, {91, 1, 2}, {60, 2, 0}};
190         assertEquals( "chi-square test statistic", 9.67444662263,
191                 testStatistic.chiSquare(counts), 1E-9);
192         assertEquals("chi-square p-value", 0.0462835770603,
193                 testStatistic.chiSquareTest(counts), 1E-9);
194     }
195 }
196
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