For Immediate Release: June 7, 2012
Contact :CDC Division of News and Electronic Media
CDC Adds Cell Phone Data to Annual Behavior Survey
The 2011 Behavioral Risk Factor Surveillance System (BRFSS) reflects an adjustment in the way the Centers for Disease Control and Prevention collects and weighs data for this annual report. This year’s report includes surveys collected using cellular telephone numbers in addition to land-line telephone numbers.
Thursday, June 7th at Noon ET
The BRFSS is a state-based system of health surveys established by CDC in 1984. BRFSS completes more than 400,000 adult interviews each year, making it the largest ongoing telephone-based health survey in the world. For most state health departments, BRFSS is their sole source of state-level, population-based data about health risk behaviors, chronic disease prevalence, and availability of preventive services.
Traditionally, BRFSS interviewers relied on calls to land-line telephone numbers. However, the number of cell-phone-only households increased by more than 700 percent during 2003–2009. CDC estimates that currently 3 in 10 U.S. households have only cellular phones. These households increasingly were left out of the population that BRFSS seeks to characterize—adults aged 18 years or older who do not live in institutional settings. Cell-phone-only use is especially strong in younger age groups and among persons in certain racial and ethnic minority groups.
The new data set uses the “`iterative proportional fitting,” commonly known as “raking” method of analysis which allows CDC to use a larger number of demographic variables. This method is expected to show somewhat higher prevalence rates for some common behavioral risk factors for younger adults and certain racial or ethnic minority groups because the use of cell phone numbers has increased their level of participation.
The BRFSS changes are discussed in detail in the June 7, 2012, MMWR Policy Note “Potential Effects on Prevalence Estimates from Improvements in Weighting and Data Collection Methods — Behavioral Risk Factor Surveillance System, 2011.”
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