Stability of sample quality for a national random-digit dialing cellular phone survey of young adults.

During the 2000s, rapid adoption of cellular phones and foregoing of landline telephones (i.e., wireless substitution) were observed (1–3). This affected behavioral surveillance by creating a staggering decrease in coverage for surveys that relied on random-digit dialing (RDD) sampling, resulting in biased health estimates (1–5). During this time, innovative sampling approaches that integrated both landlines and cellular phones were developed (6). Recently, some have suggested that the rate of wireless substitution has reached the point at which it is no longer necessary to sample landlines (7, 8). Indeed, the 2011 National Young Adult Health Survey (NYAHS), a national cellular phone–only RDD survey, demonstrated equal sample quality and some efficiency relative to the Behavioral Risk Factor Surveillance System, which samples both landlines and cellular phones (7). Emergent communication technologies continue to be rapidly adopted. There has been a dramatic increase in smartphone use, particularly among males, younger adults, and minorities (9). These devices have communication abilities beyond those of traditional cellular phones that provide users alternative ways to communicate instantly (e.g., chat functions, social media), and these functions have been adopted rapidly in recent years (10). In the context of telephone survey methodology, perhaps the most worrisome development is technologies to verbally communicate via smartphone applications without using a telephone number. Young adults, men, and Latinos are most likely to use such features (10). Cellular phones are now used less as “traditional” telephones and more as broad communication and media devices. Although the impact of this technological advance onRDD sampling of cellular phones is not known, it may affect cellular phone surveys in a manner similar to that in which wireless substitution affected landline surveys. As such, we seek to answer 2 questions. 1) Is the use of cellular phone RDD a stable method of sampling? 2) Has the sample representativeness changed (i.e., deteriorated or improved) for population subgroups?