Die gebruik van effekgrootte-indekse by die bepaling van praktiese betekenisvolheid : research and review article

Die bepaling van betekenisvolheid van verskille in gemiddeldes of dié van verbande tussen veranderlikes is in baie empiriese studies belangrik. Gewoonlik word net die statistiese betekenisvolheid gerapporteer, wat egter nie noodwendig op belangrike (prakties betekenisvolle) verskille of verbande dui nie. By studies gebaseer op waarskynlikheidsteekproewe behoort effekgrootte-indekse ook gerapporteer te word om aanvullend tot die statistiese betekenistoets uitspraak oor die praktiese betekenisvolheid te kan gee. Waar met volledige populasies of gerieflikheidsteekproewe gewerk word, is bepaling van statistiese betekenisvolheid streng gesproke nie van toepassing nie en lewer effekgrootte-indekse 'n basis om betekenisvolheid te kan beoordeel. In hierdie artikel word die aandag gevestig op die gebruik van effekgrootte-indekse om praktiese betekenisvolheid te bepaal. Verder word gewys op die gebruik daarvan in 'n paar toepassingsvelde van statistiek asook hoe dit aandag kry in die statistiese literatuur en rekenaarpakkette. Die gebruik van effekgroottes word toegelig deur enkele voorbeelde uit die navorsingsliteratuur. End The use of effect size indices to determine practical significanceThe determination of significance of differences in means and of relationships between variables is of importance in many empirical studies. Usually only statistical significance is reported, which does not necessarily indicate an important (practically significant) difference or relationship. With studies based on probability samples, effect size indices should be reported in addition to statistical significance tests in order to comment on practical significance. Where complete populations or convenience samples are worked with, the determination of statistical significance is strictly speaking no longer relevant, while the effect size indices can be used as a basis to judge significance. In this article attention is paid to the use of effect size indices in order to establish practical significance. It is also shown how these indices are utilized in a few fields of statistical application and how it receives attention in statistical literature and computer packages. The use of effect sizes is illustrated by a few examples from the research literature. End