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Two Emerging Issues in Epidemiologic Research Access to populations for epidemiologic study Side effects of specialization
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Issue #1: Access to Populations for Epidemiologic Study Often use pre-existing data But need primary data collection when: –No surveillance system exists –Need exposure data not already available Common situation: population-based case- control study
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Present in ~95% of U.S. households Used for sampling, data collection, or both Random digit dialing (RDD) –Yields probability sample –Captures unlisted phone numbers
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Number of MedLine Citations with “Random digit” and “Epidemiologic-methods” by Year
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Now-Standard RDD Refinements Distribution of calls among weekday, evening, weekend Later recontacting and conversion of “soft refusers” High-yield sampling methods: –Mitofsky-Waksberg two-stage sampling –List-assisted sampling
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Are RDD response rates declining?
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Reported Participation among Controls in 69 Case-Control Studies, by Year of Publication (Olson, 2001) Source: Am J Epidemiol 2001; 154:574-81
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Trend in Response Rates in CDC Behavioral Risk Factor Surveillance System, 1994-2000 Source: BRFSS 1998-9 Quality Control Reports
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Trend in Calling Effort in Behavioral Risk Factor Surveillance System, 1995-1999 Source: BRFSS 1999 Quality Control Report
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“And to think if I hadn’t been home having dinner I might have missed this wonderful investment opportunity.”
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Impact of Telemarketing in the U.S. Employed ~6 million people in 2001 Generated $257 billion in direct sales to consumers in 2000 ~19 billion telemarketing dialings each month “SUGging” - Selling Under the Guise of a survey “FRUGging” - Fund Raising Under the Guise of a survey
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Other Contributing Factors More single-person households More households in which all adults work outside the home Answering machines Caller ID
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“I don’t know why - I just suddenly felt like calling.”
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“As of July 2002 CMS will no longer release the Medicare Names and Addresses file to researchers. CMS has imposed a moratorium on the release of this file as means for notifying beneficiaries about research studies. “We are reevaluating our procedures to ensure that we continue to have in place the best privacy protections for Medicare beneficiaries.” Source: www.cms.gov/data/requests/moratorium.asp, accessed 6/5/03 Center for Medicare and Medicaid Services Moratorium
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Some Unfortunate Possible Responses Use only pre-existing data Use only populations of convenience –Self-identified volunteers –Existing samples from prior studies –Familiar, easy-access settings: workplaces, etc. Shift work abroad
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Some General Measures We Can Take Work toward more standardized reporting of study participation Promote a positive public image of epidemiologic research –Feed back interesting information to participants –Be mindful of respondent burden –Minimize discomfort Scrupulously protect privacy and confidentiality
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Specific Coping Strategies: 1. Worry More Selectively? Bias due to non-response depends on: (a) Proportion who participate (b) Extent of difference between participants and non-participants Sometimes (b) is small But can’t always predict when
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Specific Coping Strategies: 2. More Incremental Improvements to RDD For example... Use answering-machine messages to distinguish research from telemarketing Increase number of call-backs Optimize selection and training of interviewers Offer incentives for participation
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The National “Do Not Call” Registry
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Percentage of U.S. Households with Internet Access by Annual Household Income, 2001 Source: Bureau of the Census Current Population Survey Percentage of Households
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Possible Future Portals of Access to Populations: 1. Internet Useful data-collection method once study participation arranged Not (yet?) a promising successor to RDD for sampling
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Possible Future Portals of Access to Populations: 2. Cellular Phones Linked more to individuals, not households Population coverage may become very high Fewer calling plans charge for incoming calls Text messaging or other features may permit initial contact without annoying interruptions
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Some Currently Available Alternatives Area sampling Lists –Commercial mailing lists –Drivers license records –Voter registration lists –Other: town lists, dwelling units, etc.
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Issue #2: Side Effects of Specialization How epidemiologists vary: Chronic disease / Infectious disease Clinical training / Non-clinical background Academia / Government / Industry / Other Basic research / Field epidemiology By disease or exposure area
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Side Effects of Specialization Fragmentation and compartmentalization Risk of intellectual isolation from each other
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Divisions and Interdependencies Chronic disease / Infectious disease Clinical training / Non-clinical background Academia / Government / Industry / Other Basic research / Field epidemiology By disease area or exposure area
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Thank you
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