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General Information
Background of Florida BRFSS: Florida is one of 50 states
conducting the Behavioral Risk Factor Surveillance System (BRFSS) with financial
and technical assistance from the Centers for Disease Control and Prevention
(CDC). This state-based telephone surveillance system is designed to collect
data on individual risk behaviors and preventive health practices related to the
leading causes of morbidity and mortality in the United States. Information from
the survey is used for health planning, program evaluation, and monitoring
health objectives within the Department of Health.
Questions Asked in BRFSS: The BRFSS questionnaire is jointly
developed by CDC and state. Core questions are provided by CDC, and states are
asked not to make any changes to these questions. Rotating core questions are
those questions asked every other year. The emerging core is a set of questions,
also called a test module, that typically focus on issues of a "late
breaking" nature and are evaluated at the end of one year to determine
their potential value in future surveys. The BRFSS also includes optional
modules provided by CDC, which are sets of questions on selected topics. States
may choose to add any of the modules. States can add their own original
questions.
Available Modules 1986-2010
Target population of BRFSS is people 18 years and older, who
reside in Florida household. In Florida, BRFSS started in 1986. Since then, it
has been conducted annually. Sample Size
and Response Rate, 1986-2010
BRFSS Sampling Methods: Florida is using the disproportionate
stratified sampling (DSS) from the 1999 survey. In DSS, phone numbers were drawn
from two sets of telephone number blocks, and one adult is selected from one
telephone number
(Flow Chart of DSS). First, CDC purchases a list of randomly
selected telephone numbers and provides it to each state. Then, as you can see
from the flow chart, there are standard procedures to follow. If there is no
answer, the interviewer redials up to 15 times across a period of time. If
interviewer reaches a nonworking number or a business, calls to that number
stop. If the interviewer reaches a household with more than one adult 18 or
older, one of them is randomly selected for the interview.
Stratification: Prior to 2003, the Florida sample was
stratified by seven regions, which were groups of counties that were contiguous
but otherwise might have little in common with each other. From 2003 through
2006, Florida used three strata groups based on county population size: small
(less than 50,000), medium (50,000-299,999) and large (300,000 or more), and a
fourth stratum was added from 2004 through 2006 that sample areas with telephone
exchanges that are known to have at least 45% minority households. In 2007 and
2010, the
Florida sample has been stratified by county to ensure more useful estimates at
the local level.
Weighting Adjustment: After the data collection is completed,
data is cleaned and weighted by CDC. Data weighting is an important statistical
process that attempts to remove bias in the sample. BRFSS data set is weighted
by density status, geographic region, number of residential telephone numbers,
number of adults, age, gender and race/ethnicity.
Data Analysis: As we have seen so far, BRFSS is not based on
simple random sampling. Because of this fact, we recommend that SAS/SUDAAN
software be used to conduct data analysis. Confidence intervals are an important
measures of the role of chance.
Data Collection: BRFSS data is collected by calendar year.
Since 2000, the Florida Department of Health has contracted out the BRFSS data
collection to a survey company. Data are collected through monthly telephone
interviews, and the Department of Health regularly monitors interviews to
maintain and ensure data quality. At the completion of the interviewing cycle
each month, the survey company sends the data to CDC. At the end of the year,
the CDC aggregates monthly data for the entire year. The Department of Health
usually receives the annual dataset from the CDC in late spring following the
survey administration year.
What DOH Can Provide: There is no charge to use BRFSS data. The
data request form is available in this site. We can also provide technical
assistance for those interested in conducting their own data analysis with SAS
or SUDAAN. Prevalence data for the major questions is available at CDC BRFSS
website at
http://www.cdc.gov/brfss/.
At this website, you can view the
estimated prevalences with 95% confidence intervals by demographic break down
such as age gender race/ethnicity and socioeconomic status.
Contact
Kimberly Cohen, JD, MSW
BRFSS Coordinator.
Florida Department of Health
Bureau of Epidemiology
4052 Bald Cypress Way, Bin# A-12
Tallahassee, FL, 32399-1720
Phone: 850-245-4415
Fax: 850-922-9299
CDC Behavioral Risk
Factor Surveillance System
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