class Tryouts::Stats

def sdev
  # (sqrt( ((s).sumsq - ( (s).sum * (s).sum / (s).n)) / ((s).n-1) ))
  begin
    Math.sqrt( (@sumsq - ( @sum * @sum / @n)) / (@n-1) ).to_f
  rescue Errno::EDOM
    0.0
  end
end