A mall-intercept personal interview is a survey whereby respondents are intercepted in shopping malls or other public space. The process involves stopping shoppers, screening them for appropriateness, and either administering a survey (or interview) on the spot or inviting them to a research facility located in the mall to complete the interview. While not representative of the population in general, shopping mall customers do constitute a major share of the market for many products.
Traditionally data collection for these surveys is done with the help of a person collecting data with pen and paper in a shopping mall. With advancement in technology, it is now being done on ipad, Android tablet or iphone.
References
Mall-intercept personal interview Wikipedia(Text) CC BY-SA