Define “experimental design” in evaluation research.

Experimental design in evaluation research is defined as a research approach that incorporates random assignment to different groups in order to assess the effects of an intervention or program. This method is fundamental because it helps to isolate the effect of the program being evaluated by controlling for confounding variables. By randomly assigning participants to either a treatment group (which receives the intervention) or a control group (which does not), researchers can draw more reliable conclusions about the causal relationships between the intervention and the outcomes observed.

This design is particularly powerful in establishing causality since it minimizes biases that could occur if participants were not randomly assigned. It allows for robust statistical analysis to compare outcomes between groups, thereby providing rigorous evidence on the effectiveness of programs.

Other choices, such as those focusing on survey distribution or observational research, do not employ randomization and therefore lack the same level of control over external variables. Designs centered around case studies also do not typically involve the random assignment process essential for determining causal relationships in a structured way. Hence, the specified characteristics of experimental design are critical for evaluating program impacts effectively.