The External Validity of Experiments

TLDR

Campbell and Stanley’s 1963 book became a classic in educational experimentation, yet few subsequent works have extended its pioneering approach. The 1966 study aimed to identify sources of external invalidity arising from the reactive effect of measurement. The authors produced a work similar in purpose to achieve this goal. References include Webb et al.

Abstract

Shortly after publication, Donald T. Campbell and Julian C. Stanley's Experimental and Quasi-Experimental Designs for Research on Teaching (1963) gained the status of a classic exposition of experimentation in education. There have been few attempts to extend this pioneering work, as might be expected of a work so comprehensive in conception and so brilliant in execution. Webb et al. (1966) produced a work similar in purposethat being to identify sources of external invalidity which arise from the reactive effect of measurement. We know of no other