Differences among evaluators and approaches over the years comes from Stevenson and Thomas (2006)
One useful framework for explaining the differences among evaluators and approaches over the years comes from Stevenson and Thomas (2006), who ana- lyzed what they called the intellectual contexts for evaluation. They identified three traditions in evaluation that are closely tied to one’s original training and discipline:
(a) The experimental tradition is composed primarily of people trained in psy- chology and sociology, and in quantitative methods with a focus on estab- lishing causality. Donald Campbell was an early leader in this tradition, moving social psychologists to think more practically about conducting useful research beyond the laboratory.
(b) The case/context tradition, led by Ralph Tyler and his student Lee Cronbach, is primarily grounded in education. This movement was rooted in testing and student assessment, but moved on to describe programs and work with teachers to gain an understanding of what was happening.
(c) The policy influence tradition is composed of people trained in political science and often working in the federal government. These leaders included Carol Weiss and Joseph Wholey. Their work on policy, which was somewhat re- moved from individual programs but tried to help elected and appointed gov- ernment officials make decisions about what to fund and the directions government should take, led to a different kind of focus on use and designs.
Although evaluators come together today at large meetings of professional associations, such as the American Evaluation Association attended by more than 2,000 evaluators, these traditions can still be seen. They learn a little from each other, but continue, often, to focus on the issues familiar to the environments in which they work and their original training. By presenting different approaches in this textbook, we hope to help readers bridge these disciplines and traditions and learn what might be valuable from each for the context in which they work.