Background
To understand the general population's health conditions and risk behaviors and evaluate the effectiveness of projects on health promotion, the Health Promotion Administration (HPA) launched the first Behavioral Risk Factor Surveillance System (BRFSS) in 2007 by referencing to the U.S. BRFSS. This telephone interview survey targets people aged 15 and above in Taiwan, focusing on health issues and behavioral risk factors. Since 2007, BRFSS has been conducted annually to monitor the current status and trends of health conditions and relevant behavior risk factors among people in Taiwan. Due to the increase of mobile phone users in the population, HPA adapted  the dual-frame design that combined landline and mobile phones survey in 2021.

Aim of the Survey
(1) To understand health conditions and relevant behavior risk factors and the varying  trends among people over 15 years old in Taiwan from the national and county/city representative survey data.
(2) To establish the nationwide and county/city-wide database of health conditions and relevant behavior risk factors of people over the age of 15, and results used as references for policy planning, surveillance, and evaluation of health promotion programs and interventions.

Content of the Survey Questionnaire
The questionnaire includes health conditions, hepatitis B or C, chronic diseases, and health-related behaviors, such as smoking, chewing betel nuts, dietary, utilization of cancer screening, heat injuries, etc.

Sampling Design
The sampling frame in the landline survey is based on the Chunghwa Telecom residential telephone directory and the National Communications Commission's Code verification and allocation of local exchanges for Fixed Communication Network services as the sampling frame. It was applied the Probability Proportional to Size (PPS) as the sampling method in landline survey. The sampling is conducted with the Random Digit Dialing principle, which selects the prefix firstly, and then randomly selects the last two or four digits of the telephone numbers with those selected area codes. After phone calls are answered, within-household sampling is conducted to pick up the qualified respondent. The sampling frame in the mobile phone survey is based on the National Communications Commission's Mobile communication network service user number allocation data. Mobile phone numbers are selected by Random Digit Dialing (RDD). The county's population size selected entries of the last five digits as the sample mobile numbers.

Survey Methods
BRFSS used the CATI (Computer Assisted Telephone Interviewing) system which integrates the computer (both hardware and software) with the telephone system and is equipped with "Within-household Sampling" function. The specialist pre-programs the survey contents and the skipping rules of questions into the CATI system. The interviewers input and record respondents' answers. The supervisors can monitor phone calls, and tackle possible errors to ensure each call complies with the standard operating procedure of the survey.

Data Process and Analysis
The survey data are checked and cleaned before analysis. Post-stratification weighting is applied, and goodness of fit test is used to determine whether the distribution of the respondents in gender, age, and residence matched the target population's characteristics to ensure a good representative of the target population.

Survey Results
Results of the survey are published in the format of survey reports, press releases, and conference or journal papers. Descriptive statistics are accessible from the Statistical yearbook of Health Promotion.