code: def _get_stddevs(self, coeffs, stddev_types):
          
  
          for stddev_type in stddev_types:
              assert stddev_type in self.DEFINED_FOR_STANDARD_DEVIATION_TYPES
  
          log_stddev = coeffs['sigma']
          ln_stddev = log_stddev*np.log(10)
  
          return ln_stddev
docs: Look up values from Table 5 on p. 483 and convert to natural logarithm.
          Interpretation of "sigma_log(Y)" as the common logarithm is based on
          the order of magnitude of the values and consistent use of "log" and
          "ln" to denote common and natural logarithm elsewhere in the paper.