title: variance vs coefficient of variation
body: <p>I need to identify which statistic let me to find on digital image which line   has the highest variation. I am using Variance (square units, calculated as numpy.var(x)) and Coefficient of Variation (unitless, calculated as numpy.sd(x)/numpy.mean(x)), but I got different values, as here:</p>
  
  <pre><code>v1 = line(VAR(x)) 
  
  v2 = line(CV(x))
  
  print(v1,v2)
  </code></pre>
  
  <p>The result:</p>
  
  <blockquote>
    <p>(12,17) </p>
  </blockquote>
  
  <p>Should not both find the same line?
  Which one could be better to use in this case?</p>