NMath User's Guide

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43.5 Parameter Estimates (.NET, C#, CSharp, VB, Visual Basic, F#)

The ParameterEstimates property on LogisticRegression gets an array of LogisticRegressionParameter estimate objects. This class tests statistical hypotheses about estimated parameters in logistic regressions:

● Value gets the value of the parameter.

● StandardError gets the standard error of the parameter.

● ParameterIndex gets the index of the parameter in the linear regresssion.

● Beta gets the standardized beta coefficient. Beta coefficients are weighted by the ratio of the standard deviation of the independent variable over the standard deviation of the dependent variable.

● ConfidenceInterval() returns the 1 - alpha confidence interval for the parameter.

● TStatistic() returns the t-statistic for the null hypothesis that the parameter is equal to a given test value.

● TStatisticPValue() returns the p-value for a t-test with the null hypothesis that the parameter is equal to a given test value versus the alternative hypothesis that it is not.

● TStatisticCriticalValue() gets the critical value of the t-statistic for the specified alpha level.

For instance, this code prints out the model parameter estimates and standard error.

Code Example – C# logistic regression

var parameterEstimates = lr.ParameterEstimates;
for ( int i = 0; i < parameterEstimates.Length; i++ )
{
  var estimate = parameterEstimates[i];
  if ( i == 0 )
  {
    Console.WriteLine( "Constant term = {0}, SE = {1}", 
      estimate.Value, estimate.StandardError);
  }
  else
  {
    Console.WriteLine( "Coefficient for {0} = {1}, SE = {2}", 
      df[i].Name, estimate.Value, estimate.StandardError);
  }
}

Code Example – VB logistic regression

Dim ParameterEstimates = LR.ParameterEstimates
For I As Integer = 0 To ParameterEstimates.Length - 1
  Dim Estimate = ParameterEstimates(I)
  If (I = 0) Then
    Console.WriteLine("Constant term = {0}, SE = {1}",
      Estimate.Value, Estimate.StandardError)
  Else
    Console.WriteLine("Coefficient for {0} = {1}, SE = {2}",
      DF(I).Name, Estimate.Value, Estimate.StandardError)
  End If
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