public double getSVarS(ClusAttributeWeights scale) {
   double result = 0.0;
   for (int i = 0; i < m_NbAttrs; i++) {
     double n_tot = m_SumWeight;
     double sv_tot = m_SumValues[i];
     result += (sv_tot - sv_tot * sv_tot / n_tot) * scale.getWeight(m_Attrs[i]);
   }
   return result / m_NbAttrs;
 }
 public double getSVarSDiff(ClusAttributeWeights scale, ClusStatistic other) {
   double result = 0.0;
   RegressionStatBinaryNomiss or = (RegressionStatBinaryNomiss) other;
   for (int i = 0; i < m_NbAttrs; i++) {
     double n_tot = m_SumWeight - or.m_SumWeight;
     double sv_tot = m_SumValues[i] - or.m_SumValues[i];
     result += (sv_tot - sv_tot * sv_tot / n_tot) * scale.getWeight(m_Attrs[i]);
   }
   return result / m_NbAttrs;
 }