self-contradiction vs variability

self-contradiction

noun
  • A statement that contains a contradiction, or a premise from which one could be derived 

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 self-contradiction and variability occurred in a corpus of books? (source: Google Ngram Viewer )