Multiple Independent Sample Kruskal Wallis Test
/*
january 2007. Annie Che <chea@stat.ucla.edu>. UCLA Statistics.
Source of example data:
Conover, W. J. Practical nonparametric statistics.
In our code, we use the exact method while the Conover book uses approximation.
The calculation formula are adapted from this reference.
*/
package edu.ucla.stat.SOCR.analyses.example;
import java.util.HashMap;
import edu.ucla.stat.SOCR.analyses.data.Data;
import edu.ucla.stat.SOCR.analyses.data.DataType;
import edu.ucla.stat.SOCR.analyses.result.TwoIndependentKruskalWallisResult;
import edu.ucla.stat.SOCR.analyses.model.AnalysisType;
public class MultiIndependentKruskalWallisExample {
public static void main(String args[]) {
double[] xA = {83, 91, 94, 89, 89, 96, 91, 92, 90};
double[] xB = {91, 90, 81, 83, 84, 83, 88, 91, 89, 84};
double[] xC = {101, 100, 91, 93, 96, 95, 94};
double[] xD = {78, 82, 81, 77, 79, 81, 80, 81};
// you'll need to instantiate a data instance first.
Data data = new Data();
/* dump all the columns you need to the data object using 'data.appendX' comment.
dump as many as you'd like.
but duplicate append will cause problem, so DO NOT append the same column more than once, please.
*/
data.appendX("Column_A", xA, DataType.QUANTITATIVE);
data.appendX("Column_B", xB, DataType.QUANTITATIVE);
data.appendX("Column_C", xC, DataType.QUANTITATIVE);
data.appendX("Column_D", xD, DataType.QUANTITATIVE);
// then use the following line to get the result.
try {
TwoIndependentKruskalWallisResult result = (TwoIndependentKruskalWallisResult)data.getAnalysis(AnalysisType.TWO_INDEPENDENT_KRUSKAL_WALLIS);
if (result != null) {
// Getting the model's parameter estiamtes, summary, and statistics.
String[] groupNames = result.getGroupNameList();
double[] rankSum = result.getRankSumList();
String tStat = result.getTStat();
String s2 = result.getSSqaured(); // i.e. s * s
String cp = result.getCriticalValue();;
String dataAndRankString = result.getDataRankInformation();;
int[] groupCount = result.getGroupCount();;
String df = result.getDegreesOfFreedom();;
String[] multipleComparisonInfo = result.getMultipleComparisonInformation();;
String multipleComparisonHeader = result.getMultipleComparisonHeader();;
System.out.println("\n\nSIGNIFICANCE LEVEL = 0.05");
System.out.println("\nDEGREES OF FREEDOM = " + df);
System.out.println("\nCRITICAL VALUE = " + cp);
System.out.println("\nT-STAITISTIC = " + tStat);
System.out.println("\nS * S = " + s2);
System.out.println("\n\nNotation: Ri -- Rank of group i; ni -- size of group i.\n");
System.out.println("\n" + multipleComparisonHeader + "\n");
for (int i = 0; i <multipleComparisonInfo.length; i++) {
if (multipleComparisonInfo[i] != null)
System.out.println("\n"+multipleComparisonInfo[i] );
}
}
} catch (Exception e) {
System.out.println(e);
}
}
}
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