97 There are several contexts in which randomization in research design is not possible. Researchers may be interested in the effects of large-scale events or policy initiatives, or of complex causal processes that cannot be replicated. Threats to external validity in randomized experiments will lead to greater dividends for some research questions in a quasi-experimental design. Quasi-experime...

This paper compares the advantages and disadvantages o f the "pre-planned" and "postplanned" approaches to evaluating program effectiveness. These evaluative approaches are compared along a number o f dimensions which include: (a) Reliability o f data and the cost o f collecting it; (b) Internal validity; (c) External validity; (d) Evaluation obtrusiveness and threat; and (e) Program goal displ...

Approaches to scientific knowledge are a bit like rabid sports rivals; often they cannot say anything nice about their own team without simulta­ neously disparaging the other side. At some level, they know these intense rivalries would not exist if the other team were not a worthy contender, but the positive aspects of the other side are seldom acknowledged. likewise, empirical social scientist...

This chapter provides a selective review of some contemporary approaches to program evaluation. One motivation for our review is the recent emergence and increasing use of a particular kind of “program” in applied microeconomic research, the so-called Regression Discontinuity (RD) Design of Thistlethwaite and Campbell (1960). We organize our discussion of these various research designs by how t...

Introduction In research, validity refers to the degree to which findings are applicable in real-life situations. Essentially, if the findings are strongly valid, it implies that they have an excellent degree of applicability. In contrast, low validity implies that the survey is not applicable in real-life situations. The specific approach used during research has strong influence on validity. ...

Trials can be described as being on a design spectrum between highly explanatory (roughly, ‘Can the intervention work?’) to highly pragmatic (‘Does the intervention work in routine care?’). A criticism levelled at trials that take a pragmatic approach is that they sacrifice internal validity for external validity, i.e. there is a trade-off to be made. Proponents of pragmatic trials argue that t...