The usual incentive worldwide for consumer groups is cash. In the Middle East, however, money is never offered. The norm is a gift reflecting the importance of the respondent, from the luxurious to the practical. The same is true in Hungary and in Brazil, where groups are seen as social occasions, participation often prompted by friends' involvement.

But what happens further up the ladder? Take high-level business samples. They require especially diplomatic recruiters and have to be incentivised in ways that appeal to their status. A period of courtship is required, the subject of the research made to sound especially alluring, and the identity of the client divulged. Money may be offered ­ to their favourite charity (a clincher in Australia) ­ but the promise of information or evidence that their participation has been really worthwhile can be much more motivating.

By contrast, in China cash is still the most important incentive. Domestic, business or opinion leaders, respondents are willing to attend groups even during office hours, for a cash reward.

In Japan, it is generally recommended that one should not attempt to interview senior executives, as no incentive is likely to persuade them ­ and their opinions are probably based on information supplied by their subordinates anyway (who will come for cash). So, money will still get bums on seats ­ but not every time!