Estimates using just cellphones track closely with full sample estimates using % Republican/lean Republican
But while cellphone surveys can produce high-quality data that in some ways are superior to results of current dual-frame (landline plus cellphone) designs, neither Pew Research Center nor the telephone survey industry more generally is poised to immediately drop landline samples. Landline interviewing is roughly 30%-50% less expensive on a per-interview basis than cellphone interviewing. As a result, landlines remain an attractive option for achieving a fixed total sample size (e.g., n=1,000), even though the effective sample size after weighting is lower than would typically be achieved dialing only cellphones.3 There are also certain topics, such as experiences of elderly Americans and voter intention in low turnout elections,4 that landlines are still particularly useful for addressing.
For key, commonly asked questions such as partisan affiliation, the difference between the published total sample estimates – based on landlines and cellphones – and estimates based just on the cellphone sample has tended to be quite small. For example, in April 2012, the share of U.S. adults identifying as Republican or leaning Republican was nearly identical when computed using the total sample (39%) versus just the cellphone sample (40%). The result was highly similar in a September 2015 survey (41% for total sample versus 42% for the cellphone sample).
The contours of trends also appear to be largely unaffected by dropping landlines. Both the total sample estimates and the cellphone sample estimates show President Obama’s job approval numbers increasing from the mid-40s to the low 50s in 2012, dipping in 2013-2014, and then rebounding slightly in 2015.
Estimates using just cellphones track closely with full  | sample estimates using  | % Republican/lean Republican  | 60%  | CELLPHONESAMPLE  | 40%  | TOTAL SAMPLE  | 20%  | 0%  | 2015  | 2012  | 2013  | 2014  | % approve of Obama's handling his job as president  | 60%  | CELLPHONESAMPLE  | TOTAL SAMPLE  | 40%  | 20%  | 0%  | 2012  | 2013  | 2014  | 2015  | Source Surveys conducted April 20125september2065  | "The Twilightof Landline Interviewing"  | PEW RESEARCH CENTER 