Defining the target population – one of the most important research questions. Generalized as the population received an audience in contact with the company in any aspect. In other words, one could identify the general population and the target audience, but the variety of areas of marketing research requires assumptions. For example, the purpose of research study may be the target audience groups, consuming goods, substitutes, former customers no longer being targeted group. Accordingly, setting the parameters determining the general population – a particular problem for each case study. The investigator should not hesitate to use screening – of 'filtering' general population for the selection of the right of the respondents. Screener – a group of questions at the beginning of the questionnaire, the answers to which determine the human involvement in the survey. Typically, researchers try not to 'blow up' screener, that is not complicate the filters, since this would lead to a more rigorous and dropping out of respondents, respectively, to waste.
On the other hand, the direct benefit of the customer – the most rigorous selection of respondents. Center for Environmental Health has much to offer in this field. The questions should meet people who can answer them, otherwise part of the respondent in the study is impractical. A good example is the recent market research specific type of food for pregnant dogs, which was participate in 1150 'pet owners' selected screener that is inconsistent with the boundaries of the study. The result – a 55-percent average fill out the questionnaire, because not all owners of the guinea pigs versed in dog food.