Aggregate%20data

1
Aggregate data

• Also called summary data, tabular data
• Counts of things for places (e.g. counties) or
  entities
• Examples
• census volumes
• HSUS
• ICPSR files
• NHGIS

2
Published Census Volumes

• http//www.census.gov/prod/www/abs/decennial/

3
Historical Statistics of the United States

• http//www.cambridge.org/us/americanhistory/hsus/r
  eviews.htm

4
ICPSR Files 1 and 3

• United States Historical Election Returns,
  1824-1968
• Historical, Demographic, Economic, and Social
  Data The United States, 1790-1970
• Historical census browser
• http//fisher.lib.virginia.edu/collections/stats/h
  istcensus/

5
NHGIS

• http//www.nhgis.org
• http//www.socialexplorer.com

6
Uses of aggregate data

• Making pretty maps
• Spatial analysis (e.g. residential segregation)
• Ecological analysis
• Multi-level analysis (or contextual) in
  combination with microdata
• Aggregate data are often the only alternative
  (confidentiality, lost forms)

7
WHAT ARE MICRODATA?
Individual-level data every record
represents a separate person all of their
individual characteristics are recorded
users must manipulate the data themselves
Different from aggregate/summary/tabular data
a disability table from www.factfinder.census.g
ov an occupation table from a published
census volume from the library
8
1930 Census Population Schedule, made public
April 2002
9
Raw Census Microdata from IPUMS
10
IPUMS Data Structure
Household record (shaded) followed by a person
record for each member of the household
For each type of record, specific columns
correspond to different variables
11
http//www.rhd.uit.no/nhdc/micro.html
12
The Advantages of Microdata
? Combination of all of a
persons characteristics
? Characteristics of everyone with
whom a person lived
? Freedom to make any table you need
? Freedom to make models to look at
multivariate relationships