“OnTheMap” The Census Bureau’s New Tool for Residence-Workplace Analysis Fredrik Andersson and Jeremy Wu May 7, 2007 Daytona Beach, FL
Dec 24, 2015
“OnTheMap” The Census Bureau’s New Tool
for Residence-Workplace Analysis
Fredrik Andersson and Jeremy WuMay 7, 2007
Daytona Beach, FL
Overview of Presentation
1. Live demo of OnTheMap (Jeremy)2. The Disclosure Avoidance Protocol
for OnTheMap (Fredrik)3. Analytical validity and
confidentiality protection (Fredrik)4. Data Access (Fredrik)
1. Demonstration of OnTheMap
www.census.gov (Local Employment Dynamics) (Local Employment Dynamics)http://lehd.did.census.gov
On The Map v.1LEHD’s online dynamic
mapping tool
On The Map v.1LEHD’s 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
Optional Layers
Where are Workers Residing in Sausalito, CA Employed?
Concentric Circle Report
On The Map Version 2On 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
2. The Disclosure Avoidance Protocol for OnTheMap
The Challenge: Maximize Analytical Validity of Data Subject to Strict Confidentiality Protection Constraints
Ana
lyti
cal V
alid
ity
of D
ata
Degree of confidentiality protection
Synthetic Data
Cell Suppressio
n
Basic Facts about the Disclosure Protection System for OnTheMapGoal: “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
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???
Creation of Synthetic Data
0%5%
10%15%20%25%30%35%40%45%50%
A B C D
Home Block
Likelihood Distribution
Prior Distribution
PPD for large population
PPD for small population
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/What’s the role of a prior?Q: How are the priors constructed?Q: How much weight is given to the prior?
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
3. Analytical Validity & Confidentiality Protection
The residence patterns in synthetic data mimic confidential data well
Level of protection increases as population in work block decreases
Key Properties in data, such as commute distance, are preserved in synthetic data
4. Data Access
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.
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
Cornell CISER Site
http://vrdc.ciser.cornell.edu/onthemap/doc/
• No project approval needed
• Email [email protected] to register
• Read documentation and descriptions
• Very limited support
• Not affiliated with the Census Bureau
Getting Your Feedback
Join the OnTheMap listserv:
http://lists.census.gov/mailman/listinfo/lehd-onthemap
Or send an email with Yes in the subject line to
Contact Us
Program [email protected]
General Comments/[email protected]
Websitehttp://www.census.gov (Local Employment Dynamics)
http://lehd.did.census.gov