Found the answer to my sampling question: "As described above, we will select areas for the study by taking a stratified random sample of Census tracts in large

Found the answer to my sampling question: "As described above, we will select areas for the study by taking a stratified random sample of Census tracts in large regions within the two states where median household income does not exceed the area median income. After sampling tracts, we will randomly select addresses within tracts from USPS DSF (a sampling frame of all addresses). We will screen selected addresses for eligibility, ultimately enrolling no more than one percent of individuals within a Census tract. We may use available administrative data eliminate as many ineligible households from the sampling frame as possible to cut down on recruitment and enrollment costs, but we are examining the reliability of this data during the pilot. We are contracting with a survey research firm with extensive experience fielding national studies to assist with sampling, manage recruitment, and conduct in- person enrollment and baseline surveys." To my thinking it would have been interesting to study the possible inflation effects (treat the isolated community as representative for the whole country) but I'm sure there is a good reason/past research for structuring the sample this way.