Abstract:
The objective of this article is to present the results of an investigation into the item and test
characteristics of two tests of the Potential Index Batteries (PIB) in terms of differential item
functioning (DIF) and the effect thereof on test scores of different race groups. The English Vocabulary
(Index 12) and Spelling Tests (Index 22) of the PIB were analysed for white, black and coloured South
Africans. Item response theory (IRT) methods were used to identify items which function differentially
for white, black and coloured race groups. The effects of the differences between the item characteristic
curves (ICCs) of the three race groups on the test characteristic curve (TCCs) were studied. The items
identified as biased (DIF) appeared to have a negligible effect on the test scores of Index 12 and Index
22 at the different ability levels for the groups considered. It can be concluded that the tests do not
appear to discriminate unfairly, due to DIF, against race groups.
OPSOMMING: Die doel van hierdie artikel is om die resultate van ‘n ondersoek na die item- en toetseienskappe van
twee PIB (Potential Index Batteries) toetse in terme van itemsydigheid en die invloed wat dit op die
toetstellings van rassegroepe het, weer te gee. Die Potential Index Batteries (PIB) se Engelse
Woordeskat (Index 12) en Spellingtoetse (Index 22) is ten opsigte van blanke, swart en gekleurde Suid-
Afrikaners ontleed. Itemresponsteorie (IRT) is gebruik om items te identifiseer wat as sydig (DIF) vir
die onderskeie rassegroepe beskou kan word. Die effek van die verskille in itemkarakteristieke kurwes
van drie groepe is op die toetskarakteristieke kurwe ondersoek. Dit blyk dat die items wat as DIF
geïdentifiseer is, ‘n onbenullige effek op die toetstellings van Index 12 en 22 vir die verskillende
vermoënsvlakke van die drie groepe het. Dit kom voor dat die toetse nie as gevolg van DIF onbillik
teen blank, swart of kleurlingrassegroepe diskrimineer nie.
