C:/Documents and Settings/Stephen/Desktop/Biostatistics Library and Program/Biostatistics/OddsRatioTest.cs

Go to the documentation of this file.

using System;

namespace StephenAshley.Biostatistics
{
   using NUMBER = Decimal;

   public class OddsRatioTest
   {
      public OddsRatioTest() { data = new Fields(); }

      public OddsRatioTest(Int32 a, Int32 b, Int32 c, Int32 d)
      {
         data = new Fields();
         SetA(a);
         SetB(b);
         SetC(c);
         SetD(d);
      }

      private Fields data;

      public Int32 A()
      {
         return data.iA;
      }

      public void SetA(Int32 value)
      {
         if (value < 1)
            throw new BiostatisticsException("A value in OddsRatioText less than 1.");
         data.iA = value;
      }

      public Int32 B()
      {
         return data.iB;
      }

      public void SetB(Int32 value)
      {
         if (value < 1)
            throw new BiostatisticsException("B value in OddsRatioText less than 1.");
         data.iB = value;
      }

      public Int32 C()
      {
         return data.iC;
      }

      public void SetC(Int32 value)
      {
         if (value < 1)
            throw new BiostatisticsException("C value in OddsRatioText less than 1.");
         data.iC = value;
      }
      public Int32 D()
      {
         return data.iD;
      }

      public void SetD(Int32 value)
      {
         if (value < 1)
            throw new BiostatisticsException("B value in OddsRatioText less than 1.");
         data.iD = value;
      }

      public NUMBER ChiSquared()
      {
         Int32 iATotal = A() + C();
         Int32 iBTotal = B() + D();
         Int32 iTotal = iATotal + iBTotal;
         Int32 i1Total = A() + B();
         Int32 i2Total = C() + D();

         NUMBER decResult;
         try
         {
            NUMBER decAe = (Convert.ToDecimal(iATotal) / Convert.ToDecimal(iTotal))
               * Convert.ToDecimal(i1Total);

            NUMBER decBe = (Convert.ToDecimal(iBTotal) / Convert.ToDecimal(iTotal))
               * Convert.ToDecimal(i1Total);

            NUMBER decCe = (Convert.ToDecimal(iATotal) / Convert.ToDecimal(iTotal))
               * Convert.ToDecimal(i2Total);

            NUMBER decDe = (Convert.ToDecimal(iBTotal) / Convert.ToDecimal(iTotal))
               * Convert.ToDecimal(i2Total);

            if (decAe == 0.0m || decBe == 0.0m || decCe == 0.0m || decDe == 0.0m)
               throw new BiostatisticsException(
                  "Divide by zero in ChiSquared of OddsRatioTest.");

            decResult = ((DecMath.Abs(Convert.ToDecimal(A()) - decAe) - 0.5m) *
                  (DecMath.Abs(Convert.ToDecimal(A()) - decAe) - 0.5m) /
                  decAe)
                           +
                  ((DecMath.Abs(Convert.ToDecimal(B()) - decBe) - 0.5m) *
                  (DecMath.Abs(Convert.ToDecimal(B()) - decBe) - 0.5m) /
                  decBe)
                           +
                  ((DecMath.Abs(Convert.ToDecimal(C()) - decCe) - 0.5m) *
                  (DecMath.Abs(Convert.ToDecimal(C()) - decCe) - 0.5m) /
                  decCe)
                           +
                  ((DecMath.Abs(Convert.ToDecimal(D()) - decDe) - 0.5m) *
                  (DecMath.Abs(Convert.ToDecimal(D()) - decDe) - 0.5m) /
                  decDe);
         }
         catch (Exception e)
         { throw new BiostatisticsException(e.Source + ": " + e.Message, e); }
         return decResult;
      }

      public NUMBER ConfidenceIntervalUpperLimit()
      {
         NUMBER decResult;
         try
         {
            decResult = DecMath.Exp(LogOddsRatio() +
               1.959964394569397m * StandardErrorOfLogOddsRatio());
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      public NUMBER ConfidenceIntervalLowerLimit()
      {
         NUMBER decResult;
         try
         {
            decResult = DecMath.Exp(LogOddsRatio() -
               1.959964394569397m * StandardErrorOfLogOddsRatio());
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      public NUMBER LogOddsRatio()
      {
         NUMBER decResult;
         try
         {
            decResult = DecMath.Log(OddsRatio());
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      public NUMBER OddsRatio()
      {
         NUMBER decResult;
         try
         {
            decResult = Convert.ToDecimal(A() * D()) / Convert.ToDecimal(C() * B());
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      public NUMBER P()
      {
         NUMBER decResult;
         try
         {
            decResult = Convert.ToDecimal(Distributions.ProbabilityChiSq(
               Convert.ToDouble(ChiSquared()), 1));
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      public NUMBER StandardErrorOfLogOddsRatio()
      {
         NUMBER decResult;
         try
         {
            decResult = DecMath.Sqrt(1.0m / Convert.ToDecimal(A())
               + 1.0m / Convert.ToDecimal(B())
               + 1.0m / Convert.ToDecimal(C())
               + 1.0m / Convert.ToDecimal(D()));
         }
         catch (Exception e)
         {
            throw new BiostatisticsException(e.Source + ": " + e.Message, e);
         }
         return decResult;
      }

      private struct Fields
      {
         public Int32 iA, iB, iC, iD;
      }
   }
}

---