The process
After years of experiencing rather steep, sometimes arduous, mostly adventurous, and occasionally wondrous learning curves, JvR Psychometrics has recently published the Wechsler Adult Intelligence Scales – Fourth Edition (WAIS-IV) for the South African context. This is the result of a massive national collaboration between individuals, universities, and interest groups, and incredible support from the international publisher, Pearson.
The South African adaptation process for the WAIS-IV began in 2010, when Pearson (the international copyright holder) granted us permission to adapt the WAIS-IVUK for the SA context. A panel of psychologists and anthropologists from various cultural backgrounds provided advice in the review process, and the final version of the WAIS-IVSA was consolidated in collaboration with experts and scientists from the international Wechsler research team from Pearson Assessments. Very few changes were made to items and most were made in the verbal subscales.
The sample
We began collecting data in 2012 according to very specific criteria. The requirements of the South African context demanded that the WAIS-IVSA sample include second-language English speakers. This is unique to Wechsler assessment adaptations, as they are usually standardised only using first-language speakers. The final standardisation sample has been stratified according to age, gender, and population group. With regard to educational level, the group is slightly higher educated than the general population. While there is some debate about whether the norms are representative in terms of the quality of education received, there is not a lot of clarity around how to address the question either. Additional research with the new SA adaptation will be conducted, and JvR Psychometrics will be collaborating with researchers and experts in the field to expand research using the WAIS-IVSA in clinical settings and with different education backgrounds.
The initial sample consisted of 606 individuals, which we had to supplement with 30 cases to fill gaps in the stratification. The WAIS-IVSA validation sample consisted of 463 people, 221 men (47.7%) and 242 women (52.3%), ranging in age from 16 to 83 with a mean age of 31 years (standard deviation 14.98). The majority of the participants (30.2%) had a grade 12 education. The extent to which the validation sample matched the general adult population in terms of basic demographic characteristics was examined using the data from the 2011 South African census.
The results and norms
The reliability of the scales is excellent, matching that found in the UK and US, and the factor structure of the WAIS-IVSA also reflects the same theoretical structure as the US and UK versions. The technical information is available in the WAIS-IVSA administration manual. Norm tables were created for the following age groups:
- 16-17 years
- 18-19 years
- 20 – 24 years
- 25 – 29 years
- 30 – 39 years
- 40 – 49 years
- 50 – 59 years
In addition, there are two reference norm groups: One for ages 20-35 years, and one for first-language English speakers aged 20-35 years. Additional reference norms will be created as and when data are collected. We are currently working in collaboration with the University of Kwa-Zulu Natal to add to the data in the older age groups.
Some learnings for future adaptations
One of the many lessons learnt is that it is critical to involve interest groups, subject specialists and practitioners in the adaptation process from the beginning. This is to ensure buy-in, and widens the net for collaboration. It is also critical to have researchers, academics and practitioners from as many different fields in psychology as possible participate in the process. When working with universities with students as data collectors, it works best when incorporating the research project into a class project for marks. There are also many challenges when working in rural areas and ensuring the participation of data collectors who are volunteers. The norms that are generated will also never satisfy everyone in countries with extremely diverse cultures. These lessons are useful in going forward, and when considering such projects elsewhere on the African continent. There can be many debates as to the appropriateness of these types of cognitive assessments being used in South Africa and other African countries, but if it’s what we’ve got, it’s a start, which is surely better than nothing?
By Nicola Taylor - JvR Psychometrics
