A shorter way of Enablling/Disabling a text box from RadioButton selections
This cleans it up a little.  Removes the if statement at least:

private void AllowMissingData()
{
    MissingDataValueTextBox.Enabled = AllowBlankRadioButton.Checked;
    MissingDataValueTextBox.Text = AllowBlankRadioButton.Checked ? MissingDataValueTextBox.Text : System.String.Empty;
}