摘要：Time-space sampling (TSS; also referred to as time-location sampling, TLS) and respondent-driven sampling (RDS) are strategies that can be used for sampling hard-to-reach populations, for whom it is difficult to construct a sampling frame of the individual members of the population. With proper planning, execution, weighting, and analysis of relevant sampling-related data, both strategies have the potential to produce samples that are representative of the target populations. TSS is a probability-based strategy for recruiting members of a target population congregating at specific locations and times. RDS is predicated on the recognition that project participants are better able than project staff to locate and refer to the study site other potential participants; peers from the target population with whom they have an established relationship. Capture-recapture analysis can incorporate TSS and RDS data to estimate the size of a hard-to-reach population. TSS and RDS have been used extensively around the world in public health projects with populations at high risk for HIV infection. The collective experience gained from using TSS and RDS in HIV-related projects can be valuable in using these sampling strategies with other hard-to-reach populations in projects related to economics, political science, or sociology. Although TSS and RDS have specific strengths and limitations in terms of their abilities to produce valid results that enhance generalizability of findings, the choice of a particular sampling strategy depends on characteristics of the target population and the goal and resources of the project. Proper planning, monitoring, and evaluation of the sampling strategy and attention to logistical, regulatory, and ethical considerations are important to the successful implementation and effectiveness of the sampling strategy.
