"Data collection on mobile devices opens the possibility of collecting global positioning system (GPS) coordinates, time stamps, and other forms of paradata during survey interviews, often at very low cost, and these data are increasingly used to perform real-time quality checks on collected survey data. Robert Johnston (of UNICEF) contacted Statistics without Borders (SWB) for support in analyzing the time stamps and GPS points collected during UNICEF’s nutrition surveys to validate the surveys’ sample selection techniques.

The UNICEF nutrition surveys have been conducted in West and Central Africa since 2005 and have recently transitioned to tablet computers, which allow for more paradata collection. (Paradata are data collected as a byproduct of survey data collection; see Improving Surveys with Paradata: Analytic Uses of Process Information for more information). When a frame or sample of households from alternative sources is not available (or affordable), the team of three interviewers selects a systematic sample of households in each cluster using list-and-go, giving each household the same probability of selection. At each selected household, interviewers record the height and weight of children under the age of five, as well as other household and person-level data.

Johnston’s concern was the possibility of bias in the survey data if interviewers were not following the sample selection protocol. Traditional methods to detect deviations in selection involve frequency distributions to identify clusters of outliers and route verification by supervisors; UNICEF already has integrated these procedures into an online dashboard...."


Check out AMSTAT's article to read more:

Statistics Without Borders Helps UNICEF