title: ValueError: invalid literal for int() with base 10: 'Height (mm)'
body: <pre><code>import csv
  from decimal import *
  
  def mean(data_set):
      return Decimal(sum(data_set)) / len(data_set)
  
  def variance(data_set):
      mean_res = mean(data_set)
      differences = []
      squared_res = []
      for elem in data_set:
          differences.append(elem - mean_res)
      for elem in differences:
          squared_res.append(elem ** 2)
      return mean(squared_res)
  
  def standard_deviation(data_set):
      variance_res = variance(data_set)
      return variance_res ** Decimal('0.5')
  
  if __name__ == "__main__":
      with open("dog_data.csv", "r") as csv_file:
          csv_reader = csv.reader(csv_file)
          height_data = []
          for row in csv_reader:
              height_data.append(int(row[1]))
          print "Mean: {}".format(mean(height_data))
          print "Variance: {}".format(variance(height_data))
          print "Standard Deviation:{}".format(standard_deviation(height_data))
  </code></pre>
  
  <p>Here I'm getting an ValueError: invalid literal for int() with base 10: 'Height (mm)'.. What does this mean? How do i tackle this error ?</p>