John C. Duffy is Lecturer in Statistics, University of Edinburgh and research scientist, M.R.C. Unit for Epidemiological Studies in Psychiatry. Research interests and publications in the fields of epidemiology, causal modelling, survey methodology. Particular areas of expertise include epidemiological applications in cataract, depression, alcohol-related problems and suicide. Past member of RSS Social Statistics Section Committee, President of Association of University Teachers (Scotland), joint prizewinner, best paper of 1984, study group for the use of computers in survey analysis.


Jelke G. Bethlehem studied mathematical statistics at the University of Amsterdam. After obtaining his pre-doctoral degree, he was employed as Research Worker at the Statistical Department of the Mathematical Centre in Amsterdam. His work concentrated on multivariate statistical analysis and development of statistical software.

In 1978 he joined the Department for Statistical Methods of the Netherlands Central Bureau of Statistics (C.B.S.), first as Research Worker and later as Senior Statistician. His main topics were the treatment of nonresponse in sample surveys, in which he obtained his Ph. D., and disclosure control of published survey data.

Now he is chief of the Statistical Informatics Unit (a research unit within the Automation Department), which concentrates on the development of standard software for processing survey data. The important fields of study are the Blaise System for computer assisted survey data collection and data processing, tabulation packages, and software for weighting sample survey data.


Wouter J. Keller studied Electronics (BSc, cum laude) and Applied Mathematics at the Twente University of Technology (MSc, cum laude). After his study he was employed as Associate Professor at the Institute for Fiscal Studies of the Erasmus University (Rotterdam) and obtained his PhD (cum laude) in Econometrics.

In 1979 he joined the Netherlands Central Bureau of Statistics as head of the Department of Statistical Methods and in 1987 he became the head of the Automation Department. Also since 1982 he is part-time Professor of Econometrics and Informatics at the Free University of Amsterdam.

He works nowadays mainly on Automation of Survey Processing, Computer Assisted Telephone Interviewing (CATI), Computer Assisted Personal Interviewing (CAPI), and other methods for collecting, correcting and processing survey data, software development (software for statistical and econometrical analysis and time scheduling problems), microcomputers (hardware and software, in particular statistical software), management of research and EDP projects.