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

Go to the documentation of this file.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace StephenAshley.Biostatistics
{
   using NUMBER = Decimal;

   public class CochranQGroupsCollection : GroupsCollection
   {
      public CochranQGroupsCollection() : base() { }

      public CochranQGroupsCollection(List<Group> groups) : base(groups) { }

      public override void Add(Group group)
      {
         if (group == null)
            throw new BiostatisticsException(
               "group is a null reference.");

         if (group.n() == 0)
            throw new BiostatisticsException(
               "group has no members.");

         if (groupsArray != null && k() > 0)
         {
            for (int i = 0; i < k(); i++)
            {
               if (group.n() != groupsArray[i].n())
                  throw new BiostatisticsException(
                     "Group sizes do not match.");
            }
         }

         base.Add(group);
         return;
      }

      public Int32[] B()
      {
         if (groupsArray == null)
            throw new BiostatisticsException("groupsArray is a null reference.");
         if (k() < 2)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains fewer than two Groups.");
         if (N() == 0)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains no data.");

         Int32[] arrayB = new Int32[N()];

         for (int j = 0; j < N(); j++)
         {
            arrayB[j] = 0;
            for (int i = 0; i < k(); i++)
            {
               arrayB[j] += (Int32)groupsArray[i][j];
            }
         }
         return arrayB;
      }

      public Int32 DegreesOfFreedom()
      {
         if (groupsArray == null)
            throw new BiostatisticsException("groupsArray is a null reference.");
         if (k() < 2)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains fewer than two Groups.");
         if (N() == 0)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains no data.");
         return k() - 1;
      }

      public Int32[] G()
      {
         if (groupsArray == null)
            throw new BiostatisticsException("groupsArray is a null reference.");
         if (k() < 2)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains fewer than two Groups.");
         if (N() == 0)
            throw new BiostatisticsException(
               "CochranQGroupsCollection contains no data.");
        
         Int32[] arrayG = new Int32[k()];

         for (int i = 0; i < k(); i++)
         {
            arrayG[i] = 0;
            for (int j = 0; j < N(); j++)
            {
               arrayG[i] += (Int32)groupsArray[i][j];
            }
         }
         return arrayG;
      }

      public Int32 N()
      {
         if (groupsArray == null)
            return 0;
         return groupsArray[0].n();
      }

      public NUMBER p()
      {
         return (NUMBER)Distributions.ProbabilityChiSq((double)Q(), DegreesOfFreedom());
      }

      public NUMBER Q()
      {
         Int32 [] aG = G();
         Int32 [] aB = B();
         NUMBER decA = 0.0m;

         for (int i = 0; i < k(); i++)
         {
            decA += aG[i] * aG[i];
         }

         NUMBER decB = 0.0m;

         for (int i = 0; i < k(); i++)
         {
            decB += aG[i];
         }

         NUMBER decC = decB * decB / (NUMBER)k();

         NUMBER decD = (k() - 1) * (decA - decC);

         NUMBER decE = 0.0m;

         for (int j = 0; j < N(); j++)
         {
            decE += aB[j];
         }

         NUMBER decF = 0.0m;
         for (int j = 0; j < N(); j++)
         {
            decF += aB[j] * aB[j];
         }

         NUMBER decG = decF / k();

         NUMBER decH = decE - decG;
         NUMBER decQ = decD / decH;
         return decQ;
      }
   }
}

---