public void WriteXml(XmlWriter writer)
        {
            writer.WriteAttributeString("nominal", Nominal.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("mean", Mean.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("standardDeviation", StandardDeviation.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("lowerSpecLimit", LowerSpecLimit.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("upperSpecLimit", UpperSpecLimit.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("cp", Cp.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("cpk", Cpk.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("distribution", Distribution);
            writer.WriteAttributeString("skewness", Skewness.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("kurtosis", Kurtosis.ToString(CultureInfo.InvariantCulture));
            writer.WriteAttributeString("sampleSize", SampleSize.ToString(CultureInfo.InvariantCulture));

            writer.WriteStartElement("Sample");
            Sample.WriteXml(writer);
            writer.WriteEndElement();

            writer.WriteStartElement("Estimate");
            Estimate.WriteXml(writer);
            writer.WriteEndElement();
        }