No matter where respondents are sourced, we put them through the profile questionnaire and then one at a time we distribute them according to the segments that they are allocated to in the proportions dictated within demographic groups.   We keep demographic quotas and behavioral quotas.   The system solicits respondents that are in a profile data base.   We often use respondents from multiple panels representing different sourcing.   The result is that each project sample is a very sophisticated blend of individuals chosen because they fit the model.