Key points are not available for this paper at this time.
Neil Wrigley, Cliff Guy, Richard Dunn, Larry O'Brien, The Cardiff Consumer Panel: Methodological Aspects of the Conduct of a Long-Term Panel Survey, Transactions of the Institute of British Geographers, Vol. 10, No. 1 (1985), pp. 63-76
Wrigley et al. (Tue,) studied this question.