Abstract:

Because of the qualitative nature of group discussions, they are often the subject of debate centering around two major issues. First to what extent are the results generalizable to the real world (external validity) and second what effect do certain internal phenomena such as moderator influence, treatment effect, sampling error, group interaction, etc., have on the output (internal validity). This presentation draws together from published literature a list of potential sources of bias which it is believed may interfere with internal and external validity of group discussions. These potential sources of bias were evaluated and rated (on a 5 point scale - slightly harmful to very harmful) by a panel of well known and respected group discussion moderators in Canada and the U.S.A. A consensus was reached concerning a measure of "the harmful effects" of forty-four sources of possible bias.