The data is gathered by questionnaires distributed in several ways - direct mail, inserts in publications, door to door and on guarantee cards. Consumers are encouraged to respond by various incentives - the opportunity to win a sweepstake, free samples of various products and so on. Up to 150 questions may be asked on people's behaviour and other characteristics including what they like to buy.
Advertisers sponsor questions related to the market they're interested in.
They use the names and addresses and data produced to target better. An example of this was Chivas Regal who wished to target people who drank a competitive brand of whisky. The lists produced can be rented by non-sponsoring firms. There is a further opportunity because the companies building the databases send out communications to respondees - vouchers, merchandise and so forth. The great advantage of this form of database is that you can select individuals and households based upon genuine knowledge about them as opposed to supposition.