About the Data
Behavioral Risk Factor Surveillance System
The Behavioral Risk Factor Surveillance System (BRFSS) is a state-based health survey carried out in collaboration with the Centers for Disease Control (CDC).
- In 1984, the Centers for Disease Control and Prevention (CDC) established the Behavioral Risk Factor Surveillance System (BRFSS), a state-based, cross-sectional telephone survey.
- States collect information via landline and cellular phones using a standardized questionnaire and reports data to CDC for state and national estimates. The CDC provides technical and survey methodology assistance to states and analyzes state and national level data.
- The survey collects information on health risk behaviors, preventive health practices, and health care access related to chronic disease, injury, preventable infectious diseases (collected yearly) and oral health (collected every two years) among the adult population in all 50 states, the District of Columbia, and three U.S. territories.
- National and state prevalence rates of chronic disease, health behavior risk factors and access to health care.
- Indicators of oral health:
- The number and percentage of adults ages 18 years and older who visited a dentist or a dental clinic at least once in the past year.
- The number and percentage of older adults ages 65 years and older who have had all their natural permanent teeth removed due to infection, tooth decay or gum disease.
- The number and percentage of older adults ages 65 years and older who have had at least 6, but not all of their permanent natural teeth removed due to infection, tooth decay, or gum disease.
- The number and percentage of adults 18 to 64 years who have all their permanent natural teeth.
- Each of the above measures may be analyzed by a number of population characteristics, risk factors, or health conditions, such as: age, sex, race and ethnicity, education, income, health care coverage, overall health status, disability status, mental illness status, smoking status, binge drinking, diabetes and heart disease.
- BRFSS is currently the gold standard for behavioral health surveillance. It provides national and state-level prevalence estimates of the major behavioral risk factors among adults ages 18 years and older.
- The survey collects data on actual behaviors, rather than on attitudes or knowledge. These behavioral data are useful for planning, evaluation, reporting and carrying out health promotion and disease prevention activities.
- Identify health disparities, risk factors for and patterns of disease and health behaviors over time.
- Plan, evaluate and carry out disease prevention and health promotion activities.
- Focus resources and program activities that address barriers to dental care.
- Inform educators, researchers, medical, public health, and oral health professionals, policy makers, the media and public.
- Propose and support health-related legislative initiatives.
- The CDC changed BRFSS sampling methodology and weighting, therefore it is not possible to do a trend analysis or compare 2014 BRFSS to previous years. See "How are the data collected?" below for more information.
- New sampling and weighting methodologies introduced in 2011 and 2013 have increased the representativeness of certain populations, however some racial and ethnic groups are underrepresented.
- The Centers for Disease Control sets standard protocols for data collection to ensure consistency across states and allow for state-to-state data comparisons.
- Cross-sectional (prevalence) survey design.
- Standard core questions: Must be asked of all states. Each year, the core includes questions about emerging or “late-breaking” health issues. After one year, these questions are either discontinued or incorporated into the fixed core, rotating, or optional modules.
- Rotating core questions: The portion of the questionnaire asked by all states on an every-other year basis. See "What are the oral-health related questions?"
- Optional modules: Sets of standardized questions on various topics that each state may select and include in its questionnaire. If they are modified, they are treated as state-added questions. If questionnaire versions are slip (one long, one short), then each state must conduct at least 2,500 interviews for each version to have enough responses for weighting purposes.
- State-added questions: States are encouraged to gather data on additional topics related to their specific health priorities. These additional questions are cognitively tested prior to inclusion in the questionnaire.
- Sampling method
- The sampling frame consists of landline and cellular telephone numbers that the CDC provides to states.
- Cellular telephone numbers were added to the BRFSS sampling frame in 2011, and consists of randomly generated numbers from a confirmed list of cellular area code and prefix combinations. Approximately 20% of state completed interviews are cell phone users.
- Disproportionate stratified sampling (DDS) has been used for the landline sample since 2003. DDS draws telephone numbers from two strata (lists) that are based on the presumed density of known landline household numbers. DDS attempts to find a way of differentiating, before sampling begins, between a set of telephone numbers that contains a large portion of target numbers (high density block) and a set that contains smaller portions of target numbers (medium density block).
- High density stratum (listed 1+ block telephone numbers) are sampled at the highest rate compared to medium density (not listed 1+ block telephone numbers) stratum.
- The rate at which each stratum is sampled is called the sampling rate. The ratio of the sampling rate of one stratum to sampling rate of a reference stratum is called the sampling ratio. For BRFSS the landline sampling ratio of high to medium density is 1:15.
- Household sampling requires interviewers to collect information on the number of adults living within a residence and then select randomly from all eligible adults. Cellular telephone respondents are weighted as single adult households.
- Geographic stratification: The BRFSS samples landline telephone numbers based on substrate geographic regions. Regional sampling is used to target data collection to geographic subpopulations (such as residents within a public health district). Large numbers of geographic strata increase costs but can provide information regarding smaller areas. Beginning in 2013, BRSS included cellular telephone stratification, although geographic specificity is less reliable for cellular than landline numbers.
- The sampling frame consists of landline and cellular telephone numbers that the CDC provides to states.
- Sample size refers to the number of telephone numbers that must be called within a given period of time. The BRFSS goal is to support at least 4,000 interviews per state each year. Factors influencing sample size include the cost involved in data collection for a larger sample and the state’s need for obtaining estimates for subpopulations (e.g. race and ethnicity).
- At least 15 call attempts per phone number are made. Surveys are conducted 20% on weekdays and 80% on weeknights and weekends. Weekdays are also reserved for callback appointments.
- Response rate refers to the proportion of completed interviews (at least age, sex, and race is collected) to phone numbers that were eligible for an interview, but refused or had an incomplete interview.
- Based on set standards of the American Association of Public Opinion Research (AAPOR), disposition codes are assigned for each calling number indicating: a completed interview, or a household was eligible, but interview not completed or telephone was ineligible or could not have its eligibility determined. These codes are used to calculate response rates, cooperation rates, and refusal rates.
BRFSS response rates by phone sampling type, 2014 Landline Cell phone Combined United States 48.7% 40.5% 47.0% Minnesota 58.7% 47.6% 54.4%
- To ensure data quality, states use monthly callback verification procedures with a 5% random sample unless electronic monitoring is used.
- Eligibility is defined as a housing unit within the state conducting the survey that has a separate entrance, where occupants eat separately from other persons on the property, and that is occupied by its members as their principal or secondary place of residence for more than 30 days per year (does not include vacation homes, group homes, and institutions). Since 2011, BRFSS considers adult students living in college housing as an eligible household.
- Eligible household members include all related adults (18 years and older), unrelated adults, boarders/roomers, and domestic workers who consider the household their home.
- Since 2011, BRFSS considers adult students living in college housing as 1 eligible household even if occupied by more than one student.
- Cellular phone numbers are treated as one-person households.
- Proxy interviews are not allowed. Individuals must respond for themselves.
- Weighting: Data weighting is an important statistical process that attempts to remove bias in the sample. The BRFSS weighting process includes two steps: design weighting and iterative proportional fitting (also known as "raking" weighting).
- Raking was added in 2011 to ensure data is representative of the population on an increased number of characteristics, including sex, age, race, education, marital status, home ownership, phone ownership (landline, cellular or both) and sub-state region.
- Because raking considers each of the weighting variables separately, there is less likelihood that categories of age and/or race would be collapsed than under previous weight methods.
- Design Weighting takes into account the number of phones and the number of adults in each household. It takes into account the number of available records (NRECSTR) and the number of records selected (NRECSEL) within each geographic strata (_GEOSTR) and density strata (_DENSTR). Design weights are calculated for landline respondents. Since state level characteristics of cellular telephone only households is not available, the design weight for cellular respondents is set to 1.
- The stratum weight (_STRWT) is calculated from the number of records in the strata and the number of records selected.
- The design weight is calculated in the following way within each _GEOSTR*_DENSTR combination: _STRWT = (NRECSTR/NRECSEL)
- Once the stratum weight is calculated, the number of adults within the household and the number of phones are used to calculate the design weight:
Design Weight = STRWT * (1/number of phones)*Number of adults in the household
The final weight is based on the following formula: Design Weight * Raking Adjustment
For more information visit:
|Oral health questions||Response options|
How long has it been since you last visited a dentist or dental clinic for any reason, including visits to dental specialists such as orthodontists?
How many of your permanent teeth have been removed because of tooth decay or gum disease? Include teeth lost to infection, but do not include teeth lost for other reasons, such as injury or orthodontics. If wisdom teeth are removed because of tooth decay or gum disease, they should be included in the count for lost teeth.
- Past year adult dental visits: Percentage of adults 18 years and older that reported visiting a dentist or dental clinic at least once within the past year.
- Older adult complete tooth loss: Percentage of adults 65 years and older that reported having had all their natural permanent teeth removed due to infection, tooth decay or gum disease.
- Older adult partial tooth loss: Percentage of adults 65 years and older that reported having had 1 to 31 of their natural permanent teeth removed due to infection, tooth decay, or gum disease.
- Adults with complete set of teeth: Percentage of adults 18 to 64 years that reported none of their natural permanent teeth removed due to infection, tooth decay, or gum disease.
Data indicators are population-weighted to be more representative. For more information on weighting, see Behavioral Risk Factor Surveillance System: Weighting BRFSS 2014 Data [pdf].
Past year adult dental visits: Number of adults 18 years and older that reported visiting a dentist or dental clinic at least once within the past year divided by the total number of adults 18 years and older that participated in the survey, multiplied by 100 to get a percent.
Older adult complete tooth loss: Number of adults 65 years and older that reported having had all their natural permanent teeth removed due to infection, tooth decay, or gum disease divided by the total number of adults 65 years and older that participated in the survey, multiplied by 100 to get a percent.
Older adult partial tooth loss: Number of adults 65 years and older that reported having had had 1 to 31 of their natural permanent teeth removed due to infection, tooth decay, or gum disease divided by the total number of adults 65 years and older that participated in the survey, multiplied by 100 to get a percent.
Adults with complete set of teeth: Number of adults 18 to 64 years that reported none of their natural permanent teeth removed due to infection, tooth decay, or gum disease divided by the total number of adults 18 to 64 years that participated in the survey, multiplied by 100 to get a percent.
Each data indicator may be analyzed by a number of population characteristics, risk factors, or health outcomes associated with oral health such as: age, sex, race and ethnicity, education, household income, health care coverage, disability status, mental illness status, smoking status, diabetes and heart disease.
- Age: 18 to 44 years, 45 to 64 years, and 65 years and older.
- Sex: Female or male.
- Race and ethnicity: White, Black or African American, American Indian or Alaska Native, Asian or Pacific Islander, Hispanic/Latino, or Multi-race.
- Education: Less than high school, high school diploma or general educational development, some post high school, or college graduate.
- Household income: Less than $35K or $35K and more.
- Disability status: Respondent has a disability if they answer "yes" to any of the following questions.
- Are you blind or do you have serious difficulty seeing, even when wearing glasses? (vision disability)
- Because of a physical, mental, or emotional condition, do you have serious difficulty concentrating, remembering, or making decisions? (cognitive disability)
- Do you have serious difficulty walking or climbing stairs? (mobility disability)
- Do you have difficulty dressing or bathing? (self-care disability)
- Because of a physical, mental, or emotional condition, do you have difficulty doing errands alone such as visiting a doctor’s office or shopping? (independent disability)
- Mental illness status: Respondent has a mental illness if they answer "yes" to the first question and/or 14+ days to the second question.
- Has a doctor, nurse or other health professional EVER told you that you have a depressive disorder (including depression, major depression, dysthymia, or minor depression)?
- Now thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good? Response options were none, 1-13 days, 14+ days.
- Smoking status: Current smokers are defined as answering "yes" to the first question and answering "every day" or "some days" to the second question. Former Smokers are defined as answering "yes" to the first question and answering "not at all" to the second question. Non-smokers are defined as answering "no" to the first question.
- Have you smoked at least 100 cigarettes in your entire life?
- Do you now smoke cigarettes every day, some days, or not at all?
- Health care access: Respondent has health care access if they answer "yes" to having health care coverage including health insurance, prepaid plans such as HMOs, government plans such as Medicare or Indian Health Service.
- Diabetes: Respondent has diabetes if they answer "yes" to ever being told by a doctor, nurse, or other health professional that they had diabetes.
- Heart disease: Respondent has heart disease if they answer "yes" to ever being told by a doctor, nurse, or other health professional that they had any of the following:
- Heart attack, also called a myocardial infarction
- Angina or coronary heart disease
- U.S. and state non-institutionalized (not on active duty in the Armed Forces or living in mental health facilities, long-term care facilities, nursing homes, or prisons) adults ages 18 years and older.
- Survey data is based on respondent report of risk factors, exposures, and health outcomes, and are not actual measurements such as that provided by hospitalization data or combination interview with physical examinations (e.g. CDC National Health and Nutrition Examination Survey).
- The BRFSS surveys a sample of adults 18 years or older in households selected from a list of landline and cellular phone numbers. It does not represent all Minnesota adults, such as those on active duty in the Armed Forces or those living in mental health facilities, long-term care facilities, nursing homes, or prisons.
- BRFSS is a phone-based survey. Therefore, adults who do not have access to a landline or cellular phone do not have an opportunity to respond to the survey.
- All surveys have possible selection bias, reporting bias and uneven or low response rates.
- Centers for Disease Control and Prevention, Behavioral Risk Factor Surveillance System
- Minnesota Department of Health, Center for Health Statistics, Behavioral Risk Factor Surveillance System
Minnesota Department of Health Oral Health Program (2014). Behavioral Risk Factor Surveillance System. Collected by the Minnesota Oral Health Program. St. Paul, Minnesota: MN Public Health Data Access portal. [Add URL] Retrieved month, year.
To obtain technical information including survey methodology (i.e. how participants are chosen), full-length questionnaires and full datasets by survey year, visit the Centers for Disease Control and Prevention, Behavioral Risk Factor Surveillance System.
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