What is an experimental design?
A research design where the researchers control the allocation of a treatment to the research subjects. Contrast this with an observational design, where the researchers do not have this control. Information from an experimental design is generally considered more authoritative than information from an observational design. For example, randomization is possible when the authors control group membership. Randomization provides some level of assurance that the two groups are comparable in every way except for the therapy received. Here are two examples of experimental designs:
In Adkinson (1997), 121 children with moderate-to-severe asthma were "randomly assigned to receive subcutaneous injections of either a mixture of seven aeroallergen extracts or a placebo." Since the researchers generated the sequence of random assignment, this is an experimental design.
In Bullock (1989), "80 severe recidivist alcoholics received accupuncture either at points specific for the treatment of substance abuse (treatment group) or at nonspecific points (control group)." Since the researchers controlled the nature of the accupuncture, this is an experimental design.
This webpage was written by Steve Simon on 2002-10-11, edited by Steve Simon, and was last modified on 2008-07-08. This page needs minor revisions. Category: Definitions, Category: Research designs.