Time-Location Sampling

Time-location sampling, also called venue-based or venue-day-time sampling, is a probability-sampling method for reaching populations that lack any list frame but reliably congregate at identifiable places and times. Developed and codified by Muhib, Stueve, and colleagues in a 2001 Public Health Reports article for a CDC youth study, it replaces the impossible task of enumerating a hidden population with the tractable task of enumerating the venues, days, and time slots where that population gathers. The analyst first builds an ethnographic frame of venue-day-time (VDT) units, then draws units at random, intercepts and enrolls eligible attendees on site, and finally weights respondents by how often they attend so that frequent venue-goers do not dominate the estimate. Because selection probabilities are known at each stage, the design yields defensible, variance-estimable population quantities rather than a convenience sample. For migration research it is especially valuable: day laborers at hiring corners, migrants at remittance shops, consulates, places of worship, markets, and transit hubs are mobile and unlisted, but they are observable in space and time. The method thus converts the visibility of a mobile migrant population into a genuine sampling frame.