package com.imsl.test.example.stat;

import com.imsl.stat.*;

/**
 * <p>
 * Performs Welch's <i>t</i>-test for three example data sets.
 * </p>
 *
 * @see <a href="WelchsTTestEx1.java">Code</a>
 * @see <a href="doc-files/WelchsTTestEx1.out">Output</a>
 */
public class WelchsTTestEx1 {

    public static void main(String args[]) {
        double[][] x = new double[3][];
        double[][] y = new double[3][];

        double st, sdf, sp, lowerCIDiff, upperCIDiff;

        x[0] = new double[]{27.5, 21.0, 19.0, 23.6, 17.0, 17.9, 16.9, 20.1, 21.9,
            22.6, 23.1, 19.6, 19.0, 21.7, 21.4};
        y[0] = new double[]{27.1, 22.0, 20.8, 23.4, 23.4, 23.5, 25.8, 22.0, 24.8,
            20.2, 21.9, 22.1, 22.9, 20.5, 24.4};

// second example, unequal variances and unequal sample sizes, where the smaller 
//sample has the larger variance
        x[1] = new double[]{17.2, 20.9, 22.6, 18.1, 21.7, 21.4, 23.5, 24.2, 14.7,
            21.8};
        y[1] = new double[]{21.5, 22.8, 21.0, 23.0, 21.6, 23.6, 22.5, 20.7, 23.4,
            21.8, 20.7, 21.7, 21.5, 22.5, 23.6, 21.5, 22.5, 23.5, 21.5, 21.8};

// third example, unequal variances and unequal sample sizes, where the larger 
// sample has the larger variance 
        x[2] = new double[]{19.8, 20.4, 19.6, 17.8, 18.5, 18.9, 18.3, 18.9, 19.5,
            22.0};
        y[2] = new double[]{28.2, 26.6, 20.1, 23.3, 25.2, 22.1, 17.7, 27.6, 20.6,
            13.7, 23.2, 17.5, 20.6, 18.0, 23.9, 21.6, 24.3, 20.4, 24.0, 13.2};

        for (int i = 0; i < x.length; i++) {
            WelchsTTest wts = new WelchsTTest(x[i], y[i]);
            st = wts.getTTest();
            sdf = wts.getTTestDF();
            sp = wts.getTTestP();
            lowerCIDiff = wts.getLowerCIDiff();
            upperCIDiff = wts.getUpperCIDiff();

            System.out.println("t-test statistic value: " + st);
            System.out.println("t-test degrees of freedom: " + sdf);
            System.out.println("t-test p-value: " + sp);
            System.out.println("Mean difference 95% confidence interval: ("
                    + lowerCIDiff + "," + upperCIDiff + ")");
        }
    }
}