import static java.lang.System.out;

import java.util.*;

import javastat.*;

import javastat.inference.twosamples.*;

import static javastat.util.Argument.*;

import static javastat.util.Output.*;

import javastat.util.*;

/**

*

* <p>Example: class TwoSampMeansTTest.</p>

* <p>Data Source: Anderson, D. R., Sweeney, D. J. and Williams, T. A. (2001).

* Contemporary Business Statistics with Microsoft Excel. South-Western,

* p. 395. </p>

*/

public class TwoSampMeansTTestExample

{

public static void main(String arg[])

{

double[] testdata1 = {300, 280, 344, 385, 372, 360, 288, 321, 376, 290,

301, 283};

double[] testdata2 = {276, 222, 310, 338, 200, 302, 317, 260, 320, 312,

334, 265};

DataManager dm = new DataManager();

TwoSampMeansTTest testclass1 =

new TwoSampMeansTTest(0.05, 0, "equal", testdata1, testdata2);

double testStatistic = testclass1.testStatistic;

double pValue = testclass1.pValue;

double lowerBound = testclass1.confidenceInterval[0];

double upperBound = testclass1.confidenceInterval[1];

TwoSampMeansTTest testclass2 = new TwoSampMeansTTest();

double[] confidenceInterval = testclass2.confidenceInterval(0.05,

testdata1, testdata2);

testStatistic = testclass2.testStatistic(0, testdata1, testdata2);

pValue = testclass2.pValue(0, "greater", testdata1, testdata2);

Hashtable argument1 = new Hashtable();

argument1.put(ALPHA, 0.05);

argument1.put(NULL_VALUE, 0);

argument1.put(SIDE, "equal");

StatisticalAnalysis testclass3 = new TwoSampMeansTTest(argument1,

testdata1, testdata2).statisticalAnalysis;

testStatistic = (Double) testclass3.output.get(TEST_STATISTIC);

pValue = (Double) testclass3.output.get(PVALUE);

confidenceInterval = (double[]) testclass3.output.get(

CONFIDENCE_INTERVAL);

lowerBound = confidenceInterval[0];

upperBound = confidenceInterval[1];

Hashtable argument2 = new Hashtable();

TwoSampMeansTTest testclass4 =

new TwoSampMeansTTest(argument2, null);

argument2.put(ALPHA, 0.05);

confidenceInterval = testclass4.

confidenceInterval(argument2, testdata1, testdata2);

argument2.put(NULL_VALUE, 0);

testStatistic = testclass4.testStatistic(argument2, testdata1,

testdata2);

argument2.put(SIDE, "greater");

pValue = testclass4.pValue(argument2, testdata1, testdata2);

}

}

Results:

The test statistic based on non-null constructor = 2.156

The p-value based on non-null constructor = 0.042

The confidence interval based on non-null constructor = [1.403 , 72.597]

{TEST_STATISTIC=2.156, PVALUE=0.042, DEGREE_OF_FREEDOM=22.0,

POINT_ESTIMATE_SE=17.165, POINT_ESTIMATE=37.0,

CONFIDENCE_INTERVAL=[D@1bf216a}

The test statistic based on null constructor = 2.156

The p-value based on null constructor = 0.021

The confidence interval based on null constructor = [1.403 , 72.597]

{TEST_STATISTIC=2.156, PVALUE=0.021,

CONFIDENCE_INTERVAL=[D@12ac982}

See also:

Estimation of the Difference between the Means,

Hypothesis Test about the Difference