1. MRC Unit on Anxiety Disorders, Department of Psychiatry University of Stellenbosch, Cape Town, South Africa; Department of Psychology, Faculty of the Social Sciences, University of Ibadan, Nigeria.
2. MRC Unit on Anxiety Disorders, Department of Psychiatry University of Stellenbosch, Cape Town, South Africa.
3. Centre for Statistical Consultation, Department of Statistics and Actuarial Science, University of Stellenbosch, Cape Town, South Africa.