On 3/7 Homer C. Wu wrote: "When we are conducting visitor survey with questionnaires, it has been said that the laws of probability explain why a small sample can represent a large group. 1. But what exactly are these laws? (academically or practically)....snip..." Perhaps a basic course in statistics offered at your local community college will succinctly answer your questions regarding sample size and statistical relevance. Chi square is a little complicated for an e-mail. Alternatively, obtain a copy of "Visitor Surveys: A User's Manual" published as part of the Professional Practice Series, Technical Information Service, of the American Association of Museums. Write: 1225 Eye Street, NW, Suite 200, Washington DC, 20005. There is a chapter devoted to sample size and a really good bibliography. Gutenkauf [log in to unmask]