What is the difference between the 1-year, 3-year, and 5-year estimates?
Mostly the available geography.
1-year estimate = Data for areas with populations of 65,000+
3-year estiimate = Data for areas with populations of 20,000+ (most counties)
5-year estimate = Data for all areas
Does Social Explorer contain ACS 5-year estimate data for tracts, block groups, and blocks?
tracts = YES
block groups = YES
blocks = NO
What does "owner occupied" mean? What is a tract?
Definitions of "owner occupied" and other variable and geographic terms can be found in the American FactFinder glossary.
What is the difference between ACS and Census 2000/2010 (the Decennial Census)?
In previous Decennial Censuses, a short list of questions was sent to 100% of the population (short form questionnaire). In addition, a longer set of questions was sent to a sample of the population (long form questionnaire). This long form questionnaire contained detailed questions on such things as educational attainment. In order to provide data on the population between censuses, the American Community Survey was developed. Beginning in 2010, the American Community Survey also takes the place of the long form questionnaire. Many of the detailed variables formerly in the Decennial Censuses will now only be found in the American Community Survey data.