class_docstr: Binary confusion matrix class
docstr: negative predictive value (NPV)
  NPV = TN / (TN + FN)
docstr_tok: ["negative","predictive","value","(","NPV",")","NPV","=","TN","\/","(","TN","+","FN",")"]
code: def NPV(self):
      """
      negative predictive value (NPV)
      NPV = TN / (TN + FN)
      """
      return np.float64(self.TN) / self.NegativeTest
  
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  import math
  import numpy
  import pandas
  import collections
  from pandas_ml.confusion_matrix.abstract import ConfusionMatrixAbstract
label_desc: Use image node_id 30 for calling the BinaryConfusionMatrix obj's underlying member method code with example usage: obj.NPV() and returns: unknown