Title: OnTheMap The Census Bureaus New Tool for ResidenceWorkplace Analysis
1OnTheMap The Census Bureaus New Tool for
Residence-Workplace Analysis
- Fredrik Andersson and Jeremy Wu
- May 7, 2007
- Daytona Beach, FL
2Overview of Presentation
- Live demo of OnTheMap (Jeremy)
- The Disclosure Avoidance Protocol for OnTheMap
(Fredrik) - Analytical validity and confidentiality
protection (Fredrik) - Data Access (Fredrik)
3Demonstration of OnTheMap
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7www.census.gov (Local Employment
Dynamics)http//lehd.did.census.gov
8On 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
9Optional Layers
10Where are Workers Residing in Sausalito, CA
Employed?
11Concentric Circle Report
12On 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
132. The Disclosure Avoidance Protocol for OnTheMap
14The Challenge Maximize Analytical Validity of
Data Subject to Strict Confidentiality Protection
Constraints
Synthetic Data
Analytical Validity of Data
Cell Suppression
Degree of confidentiality protection
15Basic 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
16Disclosure 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???
17Creation 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?
18Key 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
193. Analytical Validity Confidentiality
Protection
20The residence patterns in synthetic data mimic
confidential data well
21Level of protection increases as population in
work block decreases
22Key Properties in data, such as commute distance,
are preserved in synthetic data
234. Data Access
24OnTheMap 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.
25OnTheMap 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
26Cornell 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
27Getting 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
28Contact 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