19. The survey was mailed to 6,401 households in the state of Maryland, randomly selected from within each of four regions of the state. We sampled at the regional level to ensure the final data were generalizable to these distinctly different geographic and cultural areas, as well as to the state as a whole. The survey was fielded from April 11 to June 24 with a response rate of 27%. The unweighted sample margin of error is +/- 2.5 percentage points at the 95% confidence interval for the state. Methodology