Welcome to Introduction to GIS Software: QGIS, Class 5
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Introduction to GIS Software: QGIS
Ori
Diane
joins relate two datasets to each other
joins create new hybrid datasets
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"I have this spreadsheet I want to map..."
you need a file with relatable geographies
and a column in each file that relates the two
you have options when joining data:
select fields to bring from the spreadsheet
change the field prefix
what is the census?
decennial census
every 10 years
everyone is supposed to be counted
determines federal districting
American Community Survey
survey of ~295,000 addresses per month, 3.5 million per year
meant to replace the "long form" census
and keeps the data more up to date
margin of error: higher with 1-year estimates
margin of error: higher on smaller geometries
no matter which data you download, you'll need appropriate geographies to go with it
census blocks are the smallest area data is aggregated to
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blocks
block groups
tracts
tracts, population between 1,200 and 8,000, optimally 4,000
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NTAs are NYC-specific aggregations of census tracts
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downloading census data
joining census data
make sure you have the right boundary files
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AFFGEGOID and GEOID should be join-able