Cell Phone and Landline Research

Including cell phone samples with RDD landline samples in telephone surveys present many issues that researchers must consider. AP-GfK pollsters employed a telephone methodology that addressed concerns about coverage and non-response error.

Including cell phone samples with RDD landline samples in telephone surveys present many issues that researchers must consider. Now that a substantial number of people are living in households with only cell phones, one must decide whether to include a cell phone frame and, if so, whether to screen for the cell phone only (CPO) portion of the frame or to include those contacted by a cell phone number who also have a landline phone at home. Additionally, one must consider how much each frame should contribute to the total and how these sample portions should be pieced together through weighting.

AP-GfK pollsters, in conducting pre- and post-election polls, concerned about possible coverage and non-response error employed a dual-frame cell phone/landline telephone methodology. Data from these polls yield four important considerations:

1. First, we compare landline only, landline with CPO, and a dual frame approach to a reference source and show improvements in the coverage properties as cell phone sample is added, to include improvements in coverage from the application of pre-weights.
2. Second, estimates based on comparable weighting for each sample design show a consistent pattern where landline samples that include CPO or are dual frame show greater pre-election support for Obama.
3. Third, we show design effects or, conversely, effective sample sizes due to weighting and include a modeled equal dual frame design.
4. Last, we position design decisions in a cost model.

To learn how our dual-frame cell phone/landline telephone methodology works, please dowload our complimentary white paper, Cell Phone and Landline--Considerations for Sample Design, Estimates, Weighting, and Costs.

-April 2010

This content was provided by GfK Custom Research North America. Visit their website at www.gfkamerica.com or read their blog.