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

namespace Science.Statistics.BasicStatistics
{
    public class TwoSampleZTest
    {
        private double opdiff, sep;
        public TwoSampleZTest(StandardErrorAndExpectedValue input1, StandardErrorAndExpectedValue input2)
        {
            opdiff = input1.ExpectedValueForPercentage - input2.ExpectedValueForPercentage;
            sep = Math.Sqrt(input1.StandardErrorForPercentage * input1.StandardErrorForPercentage
                + input2.StandardErrorForPercentage * input2.StandardErrorForPercentage);
            zv = opdiff / sep; 
            FindpValue();
        }
        private void FindpValue()
        {
            NormalCurve nc = new NormalCurve();
            pv = (100.0 - nc.AreaBetween(-Math.Abs(zv), Math.Abs(zv))) / 2.0;
            if (pv < 0.01) c = "Reject null.";
            else if (pv >= 0.01 && pv < 1.0) c = " Reject null at 1% level.";
            else if (pv >= 1.0 && pv < 5.0) c = " Reject null at 5% level.";
            else c = "Accept null.";
        }
        private double zv;
        public double zValue
        {
            get { return zv; }
            set { zv = value; }
        }
        private double pv;
        public double PValue
        {
            get { return pv; }
            set { pv = value; }
        }
        private string c;
        public string Conclusion
        {
            get { return c; }
        }
    }
}