Abuses and misuses of statistics are frequent. This digest attempts to warn against these in three broad classes of pitfalls: sources of bias, errors of methodology, and misinterpretation of results. Sources of bias are conditions or circumstances that affect the external validity of statistical results. In order for a researcher to make…

This digest illustrates the variety of basic and theoretical issues in evaluation with which aspiring evaluators should be conversant in order to claim that they know the knowledge base of their profession. Coverage of the issues includes: the four steps in the logic of evaluation; whether qualitative evaluations are valid; whether it matters if…