We conducted a randomized experiment that evaluated how the inclusion of a Quick Response (QR) code in mailed survey recruitment materials for a sequential mixed-mode (push to web followed by self-administered mail back) survey fielded with a statewide probability address-based sample impacted survey participation. Each address was randomly assigned to receive mailed recruitment materials with either a unique uniform resource locator (URL) only or a unique URL with a QR code. The inclusion of a QR code resulted in a small (+1.31 percentage point) increase in overall participation and a small (+1.01 percentage point) increase in the share of recipients …

The inferential quality of an available data set, be it from a probability sample or a nonprobability sample, is discussed under the standard of the representativeness of a sample with regard to interesting characteristics, which implicitly includes the consideration of the total survey error. The paper focuses on the assumptions that are made when calculating an estimator of a certain population characteristic using a specific sampling method, and on the model-based repair methods, which can be applied in the case of deviations from these assumptions. The different implicit assumptions regarding operationalization, frame, selection method, nonresponse, measurement, and data processing are …