Privacy & Confidentiality

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					Privacy & Confidentiality
Presentation by Peter Thomson For the APS Statistical Network 30th October 2002
Privacy & Confidentiality

Scene Setting
Vision - Improve Australia’s Health through payments and information 2001-02 - $7.8 B program expenditure on Medicare (MDC) 2001-02 - $ 4.6 B program expenditure on PBS/RPBS 2001-02 - More than 220 million MDC services were processed 2001-02 - More than 160 million PBS/RPBS services were processed Enrolment population for Medicare is approximately 21 million More than 50,000 providers registered for MDC Other Programs Administered - Childhood Immunisation Register, Organ Donor Register, Practice Incentives Register, 30% Rebate on Private Health Insurance, DVA Treatment Accounts • Good source is www.hic.gov.au
Privacy & Confidentiality

• • • • • • • •

People Can Trust Us to Protect the Privacy of All Information We Handle
• At HIC we protect the privacy and confidentiality of all personal information • Respect our customers and always provide high quality service

Privacy & Confidentiality

Business Challenge (Case Study)
• Develop an information product that enables providers to analyse service activity by:
– – – – Division of General Practice (121 geographical) Period (quarter, annual) Category, Group, Sub Group and Item Various counts - number of services, number of patients, number of providers and dollars

Privacy & Confidentiality

Amount of Data
• The DGP site contains
– Millions of cells of data – Many cells contain small numbers – Some of these involved less than 4 providers or less than 6 patients

Privacy & Confidentiality

Business Problem/Constraint
• Concern that some people could be identified (local knowledge, combining various data sources) • HIC prides itself on appropriate release of information (personal information should not be released) • Must aim for a reasonable degree of protection against disclosure of precise information

Privacy & Confidentiality

What Options Were Considered
• • • • • Cell Suppression Random Rounding Random Perturbation Dominance Rule No Disclosure Avoidance

Privacy & Confidentiality

Evaluate Impact of Disclosure Methods on Data
• What are the Issues to Consider?
– – – – – – Impact on data Amount of data that can be released Degree of change in absolute data Impact on longitudinal trends How easy is it to automate Impact on data extraction time, reporting time & cost
Privacy & Confidentiality

Evaluate Impact of Disclosure Methods on Data (cont.)
• What are the Issues to Consider?
– How easy is it to automate checking of data in final reports – Pros & cons of each method – Feedback from stakeholders

Privacy & Confidentiality

Cell Suppression
• Cell replaced by an asterisk or symbol • Useful when accuracy in figures and consistency between tables is necessary • Good when only a few cells need suppression • Leads to wastage of information because of consequential suppression • Less easy to automate (especially if there are dependent tables)

Privacy & Confidentiality

Random Rounding
• • • • • • Each figure is rounded up or down to an integer (ie multiple of 5) Rounding up or down random based A particular cell value may vary from table to table Can lead to inconsistency in figures between tables Totals can be based on raw or random figures A cell threshold can be applied meaning rounding is applied only to some cells • Useful if many cells are below the threshold as this allows release of those cells • Inconsistencies can be handled by a disclaimer

Privacy & Confidentiality

Random Perturbation
• Introducing random noise/error to the data • Random amount of error is added to each cell • Better method for longitudinal data as it allows more subtle changes • Inconsistencies can be handled by a disclaimer • Disadvantage for HIC is that a small increase over time may appear as a large decrease

Privacy & Confidentiality

Dominance Rule
• Cells are suppressed if a certain percentage of activity is provided by a few individuals • ie say we had a 60/80 rule • Cell suppressed if 60% or more activity was provided by 1 doctor or • Cell suppressed if 80% or more activity was provided by 2 doctors • Suppressed cells set to zero • Do totals include the value of suppressed cells or not
Privacy & Confidentiality

No Disclosure Avoidance
• No privacy constraints • This maintains the integrity of the data • Does not reduce the risk that individuals will be identified • Will have significant legal and customer impact

Privacy & Confidentiality

Summary
• Disclosure avoidance is a very sensitive issue • Privacy of HIC customers’ records is of the upmost importance to HIC • All options either compromise the integrity of the data or have a degree of risk • Challenge - to find the right balance between respecting and maintaining the privacy of data versus the benefit of releasing low level data • Need to appreciate appreciate the complexity and sensitivity of each business issue & consider which technique is appropriate • Over time it may be necessary to use a different technique for the same business issue

Privacy & Confidentiality

Questions
• What are the experiences of other agencies • What entities need to be protected (ie patients, providers, practices, companies, etc.) • ??????

Privacy & Confidentiality


				
Lingjuan Ma Lingjuan Ma MS
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