public void TTestConstructorTest()
{
// Suppose we would like to know the effect of a treatment (such
// as a new drug) in improving the well-being of 9 patients. The
// well-being is measured in a discrete scale, going from 0 to 10.
//
// To do so, we need to register the initial state of each patient
// and then register their state after a given time under treatment.
double[,] patients =
{
// before after
// treatment treatment
/* Patient 1.*/ { 0, 1 },
/* Patient 2.*/ { 6, 5 },
/* Patient 3.*/ { 4, 9 },
/* Patient 4.*/ { 8, 6 },
/* Patient 5.*/ { 1, 6 },
/* Patient 6.*/ { 6, 7 },
/* Patient 7.*/ { 3, 4 },
/* Patient 8.*/ { 8, 7 },
/* Patient 9.*/ { 6, 5 },
};
// Extract the before and after columns
double[] before = patients.GetColumn(0);
double[] after = patients.GetColumn(1);
// Create the paired-sample T-test. Our research hypothesis is
// that the treatment does improve the patient's well-being. So
// we will be testing the hypothesis that the well-being of the
// "before" sample, the first sample, is "smaller" in comparison
// to the "after" treatment group.
PairedTTest test = new PairedTTest(before, after,
TwoSampleHypothesis.FirstValueIsSmallerThanSecond);
bool significant = test.Significant; // false
double pvalue = test.PValue; // ~ 0.165
Assert.IsFalse(significant);
Assert.AreEqual(0.16500, pvalue, 1e-5);
Assert.AreEqual(-1.03712, test.Statistic, 1e-5);
Assert.AreEqual(-0.8888889, test.ObservedDifference,1e-6);
}
