Written in response to George Fairweather's position concerning the use of experimental studies in evaluation, this paper highlights considerations in deciding when experimental procedures are feasible. The current debate on the use of experimental methods in evaluation is reviewed. (Author/GK)

The main features of a multiple site, structured case study design are presented. The nature of explanatory patterns, how case study investigators pursue and recognize valid patterns, and how an analyst can apply the same logic to cross-site analysis are discussed. (Author/BW)

The methodology of participant observation in evaluation research is described. The author cites examples of its use and includes references to additional sources of information. The characteristics of participant observation, appropriate circumstances for use, and specific techniques of this method are examined. (Author/DWH)

An introduction and overview to document analysis as a retrospective data collection technique are presented. (PN)

The various costs of Type I and Type II errors of inference from data are discussed. Six methods for minimizing each error type are presented, which may be employed even after data collection for Type I and which minimizes Type II errors by a study design and analytical means combination. (Author/CM)