@Override
 public int hashCode() {
   final int prime = 31;
   int result = 1;
   result = prime * result + _meanCalculator.hashCode();
   result = prime * result + _stdCalculator.hashCode();
   return result;
 }
 @Override
 public Double evaluate(final NormalVaRParameters parameters, final T... data) {
   Validate.notNull(parameters, "parameters");
   Validate.notNull(data, "data");
   double z = parameters.getZ();
   double mult = parameters.getTimeScaling();
   return z * mult * _stdCalculator.evaluate(data) - mult * mult * _meanCalculator.evaluate(data);
 }