Behavioral Risk Factor Surveillance System (BRFSS) is a state-based telephone survey which is performed in all 50 states, the District of Columbia, and three territories.
Included in the BRFSS are CDC's Healthy Days measures. More details about these measures: https://www.cdc.gov/hrqol/methods.htm
"The BRFSS survey is administered to a small random sample of the Oklahoma adult population. These data are then weighted to produce estimates of the Oklahoma adult population. Frequencies, percentages, weighted frequencies, combined years of information, and confidence intervals can be generated."
The survey is a state-based telephone survey which is "administered to a small random sample of the Oklahoma adult population."
The data is weighted based on the random sample, which is then used to create estimates.