The homeownership rate is computed by dividing the number of households that are owner-occupied by the total number of occupied housing units (ACS 5-year variables B25008_001E and B25008_002E from table B25008, respectively). A housing unit is owner-occupied if the owner or co-owner lives in the unit, even if it is mortgaged or not fully paid for. A housing unit is classified as occupied if it is the current place of residence of the person or group of people living in it at the time of interview, or if the occupants are only temporarily absent from the residence for two months or less (e.g., on vacation or a business trip). If all the people staying in the unit at the time of the interview are staying there for two months or less, the unit is considered to be temporarily occupied and classified as "vacant." Multiyear estimates from the American Community Survey (ACS) are "period" estimates derived from a data sample collected over a period of time, as opposed to "point-in-time" estimates such as those from past decennial censuses. ACS 5-year estimate includes data collected over a 60-month period. The date of the data is the end of the 5-year period. For example, a value dated 2014 represents data from 2010 to 2014. However, they do not describe any specific day, month, or year within that time period. Multiyear estimates require some considerations that single-year estimates do not. For example, multiyear estimates released in consecutive years consist mostly of overlapping years and shared data. The 2010-2014 ACS 5-year estimates share sample data from 2011 through 2014 with the 2011-2015 ACS 5-year estimates. Because of this overlap, users should use extreme caution in making comparisons with consecutive years of multiyear estimates. Please see "Section 3: Understanding and Using ACS Single-Year and Multiyear Estimates" on publication page 13 (file page 19) of the 2018 ACS General Handbook (https://www.census.gov/content/dam/Census/library/publications/2018/acs/acs_general_handbook_2018.pdf) for a more thorough clarification.
The Dartmouth Atlas of Healthcare calculates preventable hospital admissions by considering the discharges for ambulatory care-sensitive conditions from short-stay acute care hospitals per 1,000 medicare enrollees. This is measured as a 5-year average and is adjusted for age, sex, and race. For more information, see Regional and Racial Variation in Primary Care and the Quality of Care among Medicare Beneficiaries (2010) (https://www.dartmouthatlas.org/downloads/reports/Primary_care_report_090910.pdf).