Triangulation is typically perceived to be a strategy for improving the validity of evaluation findings; a strategy that will aid in the elimination of bias and allow the dismissal of rival alternative explanations of conclusions and propositions. Triangulation as a strategy in the social sciences dates to a 1959 paper by Campbell and Fiske in which they lay out the foundation for establishing the validity of measures through the application of a multitrait-multimethod matrix, a procedure involving both convergent and discriminant measures of traits. Eugene Webb coined the term, however, in 1966 in his now famous work, Unobtrusive Measures.

There are generally understood to be four types of triangulation:

• 1.
  Data triangulation, including across time, space, and person, or using several data sources
• 2.
  Investigator triangulation, or using ...