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What is the Behavioral Risk Factor Surveillance System (BRFSS)?Table of Contents:Key Points about the BRFSSThe BRFSS collects information from adults on health behaviors and preventive practices related to several leading causes of death. The BRFSS is used by all states, the District of Columbia, and three territories, through funds disbursed by CDC and supplemented by state program funds. The BRFSS provides data for many purposes:
TopicsThe BRFSS questionnaire is designed to include a core set of questions used by all states and an additional set sponsored by each state that may be derived from optional modules developed by CDC or other appropriate sources. Below is a general list of topics in either the core or the state-added portions of the annual BRFSS surveys; topics may vary somewhat from year to year.
Collecting DataSampling MethodFirst, a sample of telephone numbers is drawn from all possible area codes and three digit prefixes assigned to a state. In Washington State, a disproportionate stratified random sampling (DSS) method is used. For DSS, information obtained from previous surveys is used to classify 100-number blocks of telephone numbers into strata that are either "likely" or "unlikely" to yield residential numbers. Telephone numbers in the "likely" strata that are sampled at a higher rate than numbers in the "unlikely" strata. Once a household is selected, one adult (aged 18 or older) is randomly selected to be interviewed from each selected household. To facilitate the random selection process, the interviewer asks questions in order to construct a list of the adults from the oldest to the youngest male and then oldest to youngest female. A respondent is randomly selected from the ordered list of adults. Beginning in 2008, the land-line sample has been supplemented by a smaller cell phone only sample. Telephone numbers are sampled from the set of cell phone numbers assigned to Washington State and activated. Unlike the land-line sample, cell phone sample cannot be tested for working numbers and business numbers, so yield from a bank of 100 numbers is much smaller for the cell phone only sample. The questionnaire for the cell phone only sample includes questions to screen for adults who do not have a land line phone in their residence. Telephone MethodThe BRFSS uses telephone surveys to collect data. Adults (people aged 18 years or older) who live in households having a telephone are randomly selected for an interview. The survey is conducted in each state; calls are made seven days a week during both the daytime and the evening. Each state completes between 100 and 400 interviews each month. In Washington State in 2009, approximately 1,500 interviews are completed monthly. Like most states, Washington uses a computer-assisted telephone interviewing (CATI) software program. When a CATI program is used, a questionnaire is displayed on a computer screen during each interview, and the interviewer enters the responses directly into a computer. A CATI program offers several advantages:
LimitationsThe BRFSS relies on information reported directly by the respondent. As such, this self-reported data may be subject to a number of sources of possible error. How questions are worded my elicit responses in a certain way and can result in what is called "measurement error." Similarly, the ability of individuals to accurately recall details is subject to "response error." Because the questionnaire is asked in English and Spanish in Washington State, adults who are not able to be interviewed in English or Spanish are not included in the sample. Also, individuals without telephones are not contacted. As a result, BRFSS findings can only be generalized to English and Spanish speaking adults living in households with telephones. (Unlisted telephone numbers are included in the sample through the random dialing method that is used.) Results from the BRFSSBRFSS information has been used to track changes in behavior and to measure progress toward achieving national, state, and local public health objectives. For example, the document, Healthy People 2010: National Health Promotion and Disease Prevention Objectives, outlines the U.S. Department of Health and Human Services' strategy for improving the health of the nation. The more than 300 objectives stated in this publication are aimed at reducing risk factors for diseases and injury and at improving the use of health services. Many of these risk factors can be examined using information from BRFSS. State and local health assessment reports have relied extensively on BRFSS data to examine the attitudes and behaviors that reflect the underlying health risks and access to care for the population of Washington.
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Washington State Department of Health
Center for Health Statistics
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Last Update : 10/16/2009 10:59 AM