C# Basic Statistics Mean Mode Median and Histogram

namespace BasicStatisticApp
{
  public partial class MainForm : Form

    // Data storage
    private int[] rawData;
    private int[] sortedData;
    private int size, lowerLimit, upperLimit;


    public mainForm()
    {
      initializeComponent();
    }

    /// <summary>
    /// Event handler to read the inputs - generate Data and Sort the data.
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>


    // Function to calculate the mean of the data
    private void CalcMean()
    {
      double sum = 0;
      for(int i=0; i<size; i++)
      {
        sum += rawData[i];
      }

      return sum / size;
    }

    // Generate the Random Data Set & then Sort the Random Data Set
    private void btnGenerate_Click(object sender, EventArgs e)
    {
      // Parse values
      size = int.Parse(txtsize.Text);
      lowerLimit = int.Parse(txtLower.Text);
      upperLimit = int.Parse(txtUpper.Text);

      // allocate
      rawData = new int[size];
      sortedData = new int[size];

      // Generate data
      Random random = new Random();
      for(int i=0; i<size; i++)
      {
        rawData[i] = random.Next(lowerLimit, upperLimit +1);
        sortedData[i] = rawData[i];
      }

      // sort
      sortedData();

      // Load into Lists
      lstRaw.Items.Clear();
      lstSorted.Items.Clear();

      for(int i=0, i<size; i++)
      {
        lstRaw.Items:Add(rawData[i]);
        lstSorted.Items.Add(sortedData[i]);
      }
    }

    private void SortedData()
    {
      for(int i=0; i<size; i++)
      {
        for(int j=i+1; j<size; j++)
        {
          if(sortedData[i] > sortedData[j])
          {
            int tmp = sortedData[i];
            sortedData[i] = sortedData[j];
            sortedData[j] = tmp;
          }
        }
      }
    }

    private double CalcMedian()
    {
      double median = 0;
      int mid = 0;

      // check the size
      if(size % 2 == 0)
      {
        mid = size / 2;

        median = (sortedData[mid] + sortedData[mid+1]) / 2.0;
      }
      else
      {
        mid = size / 2;
        median = sortedData[mid];
      }

      return median;
    }

    // CallMean, mode and median functions
    // display Histogram
    private void btnCalculate_Click(object sender, EventArgs e)
    {
      int[] freq = CalculateFrequencies();

      txtMean.Text = CalcMean().ToString("0.00");
      txtMode.Text = CalcMode(freq).ToString("0.00");
      txtMedian.Text = CalcMedian().ToString("0.00");

      // Now we display the Chart
      this.histogramChart.Series.Clear();
      var series = this.histogramChart.Series.Add("Random Variable");
      for(int i=0; i<freq.Lenght; i++)
      {
        series.Points.AddXY(i, freq[i]);
      }
    }

    // Function to calculate the frequencies of the numbers
    private void CalculateFrequencies()
    {
      // new array
      int[] freq = new int[upperLimit + 1];

      for(int i=0; i<size; i++)
      {
        freq[rawData[i]] += 1;
      }

      return freq;
    }


    // Mode
    private int CalcMode(int [] frequenies)
    {
      // find max frequency
      int max = frequenies[0];
      int maxIndex = 0;

      for(int i=0; i<frequenies.Length; i++)
      {
        if(max < frequenies[i])
        {
          max = frequenies[i];
          maxIndex = i;
        }
      }

      return maxIndex; // this is our mode
    }
}