The NJBRFS query module contains incomplete data for 2018; data for the NJBRFS project were collected from January to March and October to November only and by two different survey companies. Additionally, supplemental data were received from other state BRFSS programs which conducted interviews throughout the year among New Jersey residents as part of a reciprocity agreement. Although the data meet minimum requirements to be included in the national BRFSS public-use data set, please consider the differences in collection when comparing estimates across years.

Starting in 2011, BRFSS protocol requires that the NJBRFS incorporate a fixed quota of interviews from cell phone respondents along with a new weighting methodology called iterative proportional fitting or "raking". The new weighting methodology incorporates additional demographic information (such as education, race, and marital status) in the weighting process.

These methodological changes were implemented to account for the under-representation of certain demographic groups in the land line sample which resulted in part from the increasing number of U.S. households without land line phones.

Comparisons between 2011 and prior years should therefore be made with caution.

More details about these changes are available from the CDC:

• Changes to the Behavioral Risk Factor Surveillance System FAQs
• Methodologic Changes in the Behavioral Risk Factor Surveillance System in 2011 and Potential Effects on Prevalence Estimates MMWR Report