Example 1: NormOneSample

This example uses data from Devore (1982, p335), which is based on data published in the Journal of Materials . There are 15 observations. The hypothesis is tested. The extremely large t value and the correspondingly small p -value provide strong evidence to reject the null hypothesis.

import com.imsl.stat.*;

public class NormOneSampleEx1 {
    public static void main(String args[]) {
        
        double mean, stdev, lomean, upmean;
        int df;
        double t, pvalue;
        double[] x = {
            26.7, 25.8, 24.0, 24.9, 26.4,
            25.9, 24.4, 21.7, 24.1, 25.9,
            27.3, 26.9, 27.3, 24.8, 23.6
        };
        
        /* Perform Analysis*/
        
        NormOneSample n1samp = new NormOneSample(x);
        
        mean = n1samp.getMean();
        stdev = n1samp.getStdDev();
        lomean = n1samp.getLowerCIMean();
        upmean = n1samp.getUpperCIMean();
        n1samp.setTTestNull(20.0);
        df = n1samp.getTTestDF();
        t = n1samp.getTTest();
        pvalue = n1samp.getTTestP();
        
        /* Print results */
        
        System.out.println("Sample Mean = "+ mean);
        System.out.println("Sample Standard Deviation = "+ stdev);
        System.out.println("95% CI for the mean is "+ lomean +"   "+ upmean);
        System.out.println("T Test results");
        System.out.println("df = " + df);
        System.out.println("t = " + t);
        System.out.println("pvalue = " + pvalue);
        System.out.println("");
        
                /* CI variance */
        double ciLoVar = n1samp.getLowerCIVariance();
        double ciUpVar = n1samp.getUpperCIVariance();
        System.out.println("CI variance is "+ciLoVar+"    "+ciUpVar);
        /*chi-squared test */
        df = n1samp.getChiSquaredTestDF();
        t = n1samp.getChiSquaredTest();
        pvalue = n1samp.getChiSquaredTestP();
        System.out.println("Chi-squared Test results");
        System.out.println("Chi-squared df = " + df);
        System.out.println("Chi-squared t = " + t);
        System.out.println("Chi-squared pvalue = " + pvalue);
    }
}

Output

Sample Mean = 25.313333333333336
Sample Standard Deviation = 1.5788181233652814
95% CI for the mean is 24.43901299970965   26.187653666957022
T Test results
df = 14
t = 13.03408619922945
pvalue = 3.2147173398634027E-9

CI variance is 1.3360926049992239    6.199863467239491
Chi-squared Test results
Chi-squared df = 14
Chi-squared t = 34.89733333333332
Chi-squared pvalue = 0.0015223176141821789