OnTheMap The Census Bureaus New Tool for ResidenceWorkplace Analysis

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OnTheMap The Census Bureaus New Tool for
Residence-Workplace Analysis

• Fredrik Andersson and Jeremy Wu
• May 7, 2007
• Daytona Beach, FL

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Overview of Presentation

• Live demo of OnTheMap (Jeremy)
• The Disclosure Avoidance Protocol for OnTheMap
  (Fredrik)
• Analytical validity and confidentiality
  protection (Fredrik)
• Data Access (Fredrik)

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Demonstration of OnTheMap
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www.census.gov (Local Employment
Dynamics)http//lehd.did.census.gov
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On The Map v.1LEHDs online dynamic mapping tool

• 17 states online
• Completed 12/06

• Where do workers live?
• Where do people work?
• Companion reports on age, earnings, and
  industry
• First partial synthetic data product

• User select areas
• Block is base unit for display block group is
  base unit for report
• Modular geographic layers such as community
  colleges and zip codes

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Optional Layers
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Where are Workers Residing in Sausalito, CA
Employed?
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Concentric Circle Report
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On The Map Version 2

• Up to 44 LED partner states
• Add 2004 data to 2002-2003 data
• Cross-state patterns for all states
• Enhanced multi-year reports
• Additional geographies
• Will become available in phases between April and
  September 2007

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2. The Disclosure Avoidance Protocol for OnTheMap
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The Challenge Maximize Analytical Validity of
Data Subject to Strict Confidentiality Protection
Constraints
Synthetic Data
Analytical Validity of Data
Cell Suppression
Degree of confidentiality protection
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Basic Facts about the Disclosure Protection
System for OnTheMap

• Goal to protect confidentiality while
  preserving analytical validity of data
• No cell suppression
• Synthetic place of residence data
• Workplace data protected by QWI disclosure
  protection system (dynamically consistent noise
  infusion)
• First-ever data product released by a Statistical
  Agency (Feb 2006) that relies on synthetic data
  method as its primary disclosure avoidance
  technique

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Disclosure Avoidance

• Bayesian statistical techniques to create a
  partially synthetic version of the confidential
  data
• Block of origin counts sampled from a posterior
  predictive distribution conditional on
  destination block and worker characteristics
  (earnings, industry, age, ownership sector)
• The posterior predictive distribution is derived
  from combining the likelihood (true data) with
  a prior
• So, what does this really mean???

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Creation of Synthetic Data
Fictional example Distribution of place of
residence for workers in a specific block,
industry, earnings category, age category,
ownership sector
Q Why not sample directly from the
likelihood/Whats the role of a prior?
Q How are the priors constructed?
Q How much weight is given to the prior?
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Key Implication

• The relative weight of the prior when sampling
  from the posterior distribution is inversely
  related to the size of the population being
  synthesized
• For larger populations the synthetic place of
  residence data closely mimic underlying data
• For small populations the synthetic place of
  residence data are relatively more noisy to
  protect confidentiality
• Important to keep in mind when making inferences
  using OnTheMap
• How noisy an estimate is can be assessed by
  taking advantage of all 10 implicates of the
  synthetic data available on the virtual RDC

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3. Analytical Validity Confidentiality
Protection
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The residence patterns in synthetic data mimic
confidential data well
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Level of protection increases as population in
work block decreases
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Key Properties in data, such as commute distance,
are preserved in synthetic data
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4. Data Access
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OnTheMap Data

• ------------------ (public use data)
  -------------------
• Origin-Destination (OD) matrix
• Residence Area Characteristics
• Workplace Area Characteristics
• Quarterly Workforce Indicators (QWI)
• --------------- (below not distributed)
  ---------------
• TIGER files
• Geographic shape files, etc.

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OnTheMap Data

• There are 10 implicates only the first is used
  in OnTheMap at this time
• 2002-2004
• OnTheMap v2 for 17 states to be released May 31
  these and future data to be made available within
  6 weeks of release
• OnTheMap v1 data will be withdrawn in June

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Cornell CISER Site

• http//vrdc.ciser.cornell.edu/onthemap/doc/
• No project approval needed
• Email Virtualrdc_at_cornell.edu to register
• Read documentation and descriptions
• Very limited support
• Not affiliated with the Census Bureau

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Getting Your Feedback

• Join the OnTheMap listserv
• http//lists.census.gov/mailman/listinfo/lehd-onth
  emap
• Or send an email with Yes in the subject line to
• dsd.local.employment.dynamics_at_census.gov

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Contact Us
Program Manager Jeremy.S.Wu_at_census.gov General
Comments/Suggestions Fredrik.Andersson_at_census.gov
dsd.local.employment.dynamics_at_census.gov
Website http//www.census.gov (Local Employment
Dynamics) http//lehd.did.census.gov