Meeting the challenge
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Meeting the Challenge. The National Population Health Survey and Data Access. E. Hamilton UNB Libraries IASSIST 2003. Outline. NPHS: Background & Confidentiality Challenges NPHS Products Dissemination Evaluating Success of Strategy Concluding Observations. Canadian Context.

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Meeting the challenge

Meeting the Challenge

The National Population Health Survey and Data Access

E. Hamilton

UNB Libraries




  • NPHS: Background & Confidentiality Challenges

  • NPHS Products Dissemination

  • Evaluating Success of Strategy

  • Concluding Observations

Canadian context

Canadian Context

  • Federal/provincial/territorial division of powers and responsibilities

  • Health and privacy legislated at the federal level and at the provincial level

Canadian context1

Canadian Context

  • NPHS dissemination affected by:

    • Statistics Canada Act and policies

    • Privacy Act

    • Privacy legislation at provincial levels

    • Ethics in research guidelines

Nphs background

NPHS Background

  • NHIC Task Force on the State of Health Information in Canada (1990-91)

  • Identification of data gaps and related problems in sharing health information

  • Proposal for a national health survey to provide more comprehensive information on population health status

Nphs objectives

NPHS Objectives

  • To provide measures of health status for policy

  • To provide data for analytic studies

  • To provide panel data to reflect dynamic process of health and produce periodic cross-sectional estimates

  • To provide provinces with survey capacity to supplement content or sample

  • To allow the possibility of linking survey results to administrative data


Risks …

  • More complete information being collection

  • Tools and techniques available to amass personal information

  • Increase in “market potential” of personal information

  • Potential for misuse of health information

  • Difficulty to control information use

  • Any data safety breach potentially serious to mandate of ethical data collectors

  • At the time of NPHS design, 67% of Canadians said they would oppose free sharing of health care information

And yet

And yet…

  • In the NPHS conducted in 1994/95:

  • 94% of survey respondents consented to have their data linked with administrative health records

  • 96% consented to have data shared with provincial ministries of health.

  • Between cycle 1 and cycle 2, NPHS retained 93% of longitudinal sample

Nphs administration

NPHS Administration

  • Household survey: general and health components

    • Complex survey design using strata and based on LFS frame; Respondents to be followed for 20 years

  • Institutional survey

  • Northern survey

Cycle 1 Household survey in the field in June 1994

Nphs products

NPHS Products

  • Methodology and survey documentation, articles in Health Reports, aggregate statistics in national “health report card”

  • Data products in variety of formats

  • Workshops, grants, and seminars

Nphs data products

NPHS Data Products

Meeting the challenge


Statistics Canada Website

Depository Service Program

Data Liberation Initiative

Sales & Customized Tabulations

Remote Job Submission

Research Data Centres

Who is eligible

General public

General public through DSP libraries

Post-secondary academic staff & students

Individuals or organizations

Researchers with accepted proposals

Approved researchers


Available on the Internet at

Available on site

Restricted to teaching and research purposes

Contractual; standard fees usually apply

Arrangement between STC & researcher; fee charged

SSHRC peer review & deemed STC employee status


- The Daily

- Canadian Statistics

- Census

- Community profiles

- Downloadable publications

- Paper publications

- Electronic publications & select CDs

Standard data products: aggregate databases, public use microdata files, and geography files

Standard data products; custom tables that have been processed by STC;access to specialized databases

Analytic syntax built by researcher using synthetic files, and STC processing

Confidential data files from the longitudinal surveys begun in the 1990’s, such as the NPHS, SLID, NLSCY


Warning: some services on the web site are fee-based

Some DSP libraries provide off-site access to authenticated users

Interface to CANSIM I and Trade Analyzer available through CHASS (University of Toronto)

Specialized databases include CANSIM II and the Trade Analyzer

Available for only select surveys; this service most developed for the NPHS

Applications can be submitted through the RDC/SSHRC web site

Continuum of Access to Statistics Canada Products



  • Multistage cluster sample design increases complexity (bootstrap weighting and the problem of variance)

  • Attrition in population in Institution survey

  • Linkage issues for administrative units and files

  • Supplement questions and buy-ins (and you thought life was complicated enough!)

Research project

Research Project

  • Research Objective:

    • to discover evidence of use of the NPHS, a longitudinal survey by Statistics Canada with significant confidentiality challenges

  • Methodology:

    • Using established peer-reviewed databases as well as grey literature searching techniques, sought out evidence of data use and knowledge transfer relating to the NPHS

Research findings

Research Findings

557 Items and counting!

  • 271 articles

    • 105 unique journal titles

    • 147 primary authors of articles

  • 115 conference presentations/reports

  • 31 theses / dissertations

Research findings1

Research Findings

PUMFs received greatest use in file types identified

Cycle 1 remains file with most research use*

* Cited twice in 2003

Research findings2

Research Findings

HHD cycle1

PUMF release

HHD cycle2

PUMF release

HHD cycle3

PUMF release

CCHS cycle 1.1

PUMF release



  • NPHS is a success story in getting data into the hands of analysts

  • Though concerned with privacy, respondents trust Statistics Canada enough to allow sharing of data

  • Complexity in design posed challenges for cross-sectional data file to preserve confidentiality



  • Challenge with linkage & confidentiality related to recipient community (priorities, laws, protocols)

  • Longitudinal file resolved through provision of dummy files for remote job submission & RDCs

  • Cross-sectional analysis for lower levels of geography now available through CCHS

  • Despite remarkable research outcomes, no reported breaches in confidentiality by research community

Future research

Future Research

  • Completion of grey literature tracking for NPHS to date

  • Monitoring RDC analytical output

  • Tracking CCHS research output

  • Identifying further “Best Practices” in data dissemination designed to enhance access to data while protecting confidentiality

There is more to come

There is more to come…

Thank you for your attention!

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