assessment vs datum

assessment

noun
  • An appraisal or evaluation. 

  • The act of assessing or an amount (of tax, levy or duty etc) assessed. 

datum

noun
  • A premise from which conclusions are drawn. 

  • A floating reference point, or SLDMB, used to evaluate surface currents in a body of water. Often employed by coastal search and rescue. 

  • A fixed reference point or set of reference points which precisely define a system of measurement or a coordinate system. 

  • A fact known from direct observation. 

verb
  • To provide missing data points by using a mathematical model to extrapolate values that are outside the range of a measuring device. 

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