Psychological measurement for specialists in group work

Recent articles in The Journal for Specialists in Group Work have discussed credibility indicators for quantitative and qualitative studies (Asner-Self, 2009; Rubel & Villalba, 2009). This article extends upon these contributions by discussing measurement issues that are relevant to producers and consumers of quantitative group research. This article is necessary as measurement quality is directly associated with research credibility. The topics of reliability and validity along with credibility indicators for measures are discussed. This is followed by a description of the statistical assumption of independent measurements in relationship to group research. Implications for research and practice are provided.