The mySidewalk data library supports a rich collection of US Census products that span over thirty years. Drawing on Census data as far back as 1990, mySidewalk produced future projections for over one hundred Census concepts at all 16 geography levels available in our application. 

Preparing the Data

Producing projections from historical Census data would not be possible without a few supporting procedures to prepare the data. Geographic harmonization was utilized to align data from past Census products with Census 2010 geographic boundaries. We also used the Amelia II software provided by Gary King et al. at Harvard University (see citation below) to impute missing values in the data. 

Methodology

All projections are generated from data originating from the following Census products:

  • Decennial Census 1990
  • Decennial Census 2000
  • Decennial Census 2010
  • American Community Survey (ACS) 2007-2011 5 Year Estimates (used to proxy for concepts not available in the short form Decennial Census 2010)
  • American Community Survey (ACS) 2013-2017 5 Year Estimates

Projections for over one hundred Census concepts were produced for 2017, 2019, 2021, 2023, and 2025 using a modified linear regression over the years: 1990, 2000, 2010, and ACS 2013-2017 (referred to as 2015). The slope of the regressor is standard (mainly for efficiency and to prevent overfitting), and the ACS 2013-2017 value is always used as the offset instead of the standard regression offset, as it is the last known good of the series.

Citations
James Honaker, Gary King, and Matthew Blackwell. 2011. “Amelia II: A Program for Missing Data.” Journal of Statistical Software, 45, 7, Pp. 1-47. Copy at http://j.mp/2owkPrr

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