inconsistency vs variability

inconsistency

noun
  • The state of being inconsistent. 

  • An incompatibility between two propositions that cannot both be true. 

variability

noun
  • The state or characteristic of being variable. 

  • The degree to which a thing is variable. In data or statistics this is often a measurement of distance from the mean or a description of data range. 

How often have the words inconsistency and variability occurred in a corpus of books? (source: Google Ngram Viewer )