11 520 A Workshop on Geographic Information Systems 11 188 Urban Planning and Social Science Laboratory Making Sense of the Census September 29 2010 Census Discussion Overview Utilizing Large Tabular Datasets US Census Understand key aspects of US Census Data What is it and why do we care How are the data collected What data are available Introduction to Census geography and summary levels A quick look at the Census documentation A quick look at some sample data Understand nature and use of large highly structured public datasets 2 Examine primary US Census Data SF3 Summary File 3 at the block group level Appreciate differences between Census SF3 CDs and third party census extracts Learn how to manipulate census data in MS Access and ArcGIS Example Thematic map of Income viz median earnings Isn t this easy We did thematic map of income on day 1 Yes if desired variable is already in attribute table of map There are thousands of variable in the long form census What do we mean by income Which combinations zero in on useful indicator Drilling down and combining data are often needed Household personal Earned income all income At what scale state county city tract block group For what time period weekly yearly part time 3 Example Thematic map of Income viz median earnings Example median 1999 personal earnings from the 2000 US Census Variable P85 among the hundreds of census variables and thousands of columns P85 records Median earnings in 1999 dollars by sex for the population 16 years and over with earnings The P85 table has three columns 4 earnings includes wages salaries and net self employment income but not entitlements P085001 total for universe of population 16 years old with earnings P085002 male P085003 female Example Thematic map of Income viz median earnings Use MS Access database in class locker M data census2k hw2 sf3 lite mdb Two of the 70 raw US census files for Massachusetts have already been loaded Determine the median earnings for Cambridge block groups Understand census data structure and use of raw data Examine ER diagram of relationships among the tables used in this query Illustrate SQL query development in MS Access Save query and make table to have results available in both forms 5 Example Thematic map of Income viz median earnings Map median earnings for Cambridge block groups Bring MS Access query results into ArcMap Create thematic map Examine Technical Documentation for the SF3 Census data Online site at US Census http www census gov prod cen2000 doc sf3 pdf Copy in class locker for faster access http mit edu 11 520 data census2k sf3 pdf Learn how to identify variables of interest and find them in the data tables 6 Examples Research Projects based on Census 7 Sources http livingwage mit edu http povertyinamerica mit edu What Is the Census Mandated by the Constitution of the United States Census History The first census took place in 1790 to determine the number of seats each state would have in the U S House of Representatives The census was created to gain a better understanding of where people lived and to establish patterns of settlement as the nation grew The modern census of population and housing was established in 1940 with the incorporation of the housing component and the introduction of sampling techniques for the long form Census Bureau The Census Bureau was established in 1902 Today in addition to administering the census of population and housing the Census Bureau conducts more than 200 annual surveys including the American Community Survey the Current Population Survey and economic censuses every five years 8 Source http 2010 census gov 2010census Why Do We Care U S Congressional representatives are apportioned based on census counts Federal dollars are distributed based on census for schools employment services highway assistance housing construction hospital services programs for the elderly etc Conducted every 10 years now a rolling census An actual count of entire population categorized by various criteria The only source for spatially detailed demographic data with a consistent coast to coast data structure The most reliable detailed and consistent source for describing local areas neighborhoods cities counties of time series demographic data available 9 How the Data Are Collected Collected from households through a mail survey conducted every decade For the 2000 Census 2000 Census Home Page more than 285 000 census takers and support personnel accounted for 118 million households and 275 million persons in the U S Two different census questionnaires are distributed short form questionnaire contains questions asked of everyone summarized in Summary Tape File 1 STF 1 for 1980 and 1990 Summary File SF 1 for 2000 long form questionnaire contains questions asked of a population sample 1 6 households summarized in Summary Tape File 3 STF 3 for 1980 and 1990 Summary File 3 SF 3 for 2000 The long form is being replaced in the 2010 Census by the American Community Survey ACS 10 This program will survey homes every month and provide updated statistics every year instead of every 10 years The program begins in 2003 What s Included Information on Population Employment Housing Characteristics Long Form Sample Counts STF 3 SF 3 Population Characteristics Social Characteristics Education Citizenship Ancestry Language Disability Children Place of Birth Economic Characteristics Income Labor Force Status Employment Place of Work Public Assistance Retirement Income Housing Characteristics Age of Housing Heating Fuel Facilities Vehicles Mortgage Status What s Included Information on Population Employment Housing Characteristics Short Form 100 Count STF 1 SF 1 Population Characteristics Housing Characteristics Age Tenure Gender Value or Contract Rent Race Vacancy Status Hispanic Origin Number of Rooms Marital Status Units in Structure Household Type Congregate Housing Household Relationship Why We Need to Know the Two Components Accuracy of the data varies and counts differ Why It helps us to understand how the data are organized in Summary Files SFs 12 Census Geography and Summary Levels The Census organizes and aggregates data into a series of geographic hierarchies Standard Hierarchy of Census Geographic Entities from Census 2000 Summary File 1 Technical Documentation prepared by the U S Census Bureau 2001 p A 25 13 Census Geography and Summary Levels If no line joins 2 geographic types then an absolute and predictable relationship does not exist