Better Cell Phone Sampling
There are good reasons to avoid phone surveys if you can. But if there is no alternative, it is critical to think about strategies for integrating cell phones into your outreach and sampling. Almost half (48%) of U.S. adults have no landline telephone service, while fewer than one in ten (9%) have no cell phone service. The Pew Research Center reports that its recent rigorously designed phone surveys of U.S. adults have been yielding two-thirds of all respondents on cell phones.
The options for cell phone sampling have never been great, but as cell phones become the dominant mode of voice communication, sample vendors are improving what they offer. As such, population-based phone surveys are still feasible, though still quite expensive.
Recent improvements to cell phone sample include:
- Inactivity flags. An estimated one-third of cell phone numbers generated via RDD methods are non-working. Of course numbers cycle in and out of usage, but fortunately there are ways to track, identify, and flag numbers that are no longer in service.
- Geographic targeting. Many consumers retain their cell phone numbers when they move to new areas, so roughly four in ten no longer correspond to the geographic area codes and exchanges from which they originated. Sample vendors are working around that with products that append billing zip codes or full addresses to cell phone numbers, reflecting the geography of where users actually live.
- Pre-paid flags. In the past, exchange-based geographic targeting was a useful way to find poorer people who are more difficult to locate and recruit for surveys. Today, vendors can help identify which mobile numbers are linked to pre-paid service (roughly 15% of all cell phone numbers), which is another method of improving the overall demographic profile of your sample.
If you’re a hospital, school district, park district, or municipality trying to gauge the needs of your local community, a phone survey may be the only good option you have. Just know that the landscape of how to do them continues to change dramatically, with welcome improvements on the way.
And don’t forget: never ever use auto-dialers. If you reach a cell phone number via automated dialing—even if inadvertently—it may cost you millions in government fines.