uncertainty vs validity

uncertainty

noun
  • Doubt; the condition of being uncertain or without conviction. 

  • A parameter that measures the dispersion of a range of measured values. 

  • Something uncertain or ambiguous. 

validity

noun
  • The genuinity - as distinguished from the efficacity or the regularity - of a sacrament as a result of some formal dispositions being fulfilled. 

  • The state of being valid, authentic or genuine. 

  • State of having legal force. 

  • A quality of a measurement indicating the degree to which the measure reflects the underlying construct, that is, whether it measures what it purports to measure (see reliability). 

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