From Gallup’s USA Today Blog the polling firm has been studying the effect of a growing number of “cell phone only households”.

Study after study has shown that in general, the effect of excluding from the interview process those who only have cell phones has not seemed to affect the overall marginal results of political studies.

Still, Gallup has been studying and investigating the implications of cell phone only households for well over a year now. And, as of Jan. 1, 2008, Gallup has made the decision to include cell phone interviewing as part of the sample used for its general population studies.

Check out the above linked post for more information on Gallup’s new methodology and how they will implement the cell phones and get their sample population.