public final double errorRate(){
  if (!m_ClassIsNominal) {
    return Math.sqrt(m_SumSqrErr / (m_WithClass - m_Unclassified));
  }
  if (m_CostMatrix == null) {
    return m_Incorrect / m_WithClass;
  }
 else {
    return avgCost();
  }
}

public final double errorRate ( ) { if ( ! m_ClassIsNominal ) { return Math . sqrt ( m_SumSqrErr / ( m_WithClass - m_Unclassified ) ) ; } if ( m_CostMatrix == null ) { return m_Incorrect / m_WithClass ; } else { return avgCost ( ) ; } }
returns the estimated error rate or the root mean squared error ( if the class is numeric ) . if a cost matrix was given this error rate gives the average cost .
