outcome research 1

Source of Source of data/ethical data/ethical

concernsconcernsWei-Chu ChieWei-Chu Chie

outcome research 2

Steps of a researchSteps of a research• Conceiving the research question• Choosing the study subjects• Planning the measurement• Conducting the study• Analyzing the data• Writing the report

outcome research 3

A good research questionA good research question• Feasible• Interesting• Novel• Ethical• Relevant

outcome research 4

Data: subjects and Data: subjects and measurementmeasurement

– Subjects• target population (research question)• accessible population (study plan)• intended sample (study plan)• actual subjects (actual study)

– Measurement• phenomena of interest (research question)• intended variables (study plan)• actual measurement (actual study)

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Research validityResearch validity– Internal validity

• how well the findings of the study infer to the truth of the study (study plan)

– actual subjects to intended sample– actual measurement to intended variables

– External validity• how well the truth in the study infer to the

truth in the universe (research question)– intended sample to accessible and to target

population– intended variables to phenomena of interest

outcome research 6

Source of dataSource of data• Primary

– collect original data by the researcher him or herself

• Secondary– use existing data

• Tertiary– use existing studies

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Primary data: subjectsPrimary data: subjects– Specification: target to accessible population

• target population: well suited to the research question• accessible population: representative of the target po

pulation and easy to study– Sampling: accessible population to sample

• intended sample: representative of the accessible population and easy to study

– Question of external validity (generalizability)• usually less strict in epidemiologic and clinical outco

me research

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Primary data: subjects Primary data: subjects • Inclusion criteria: be specific

– specifying the characteristics that define population relevant to the research question and easy to study• target population: demographic and clinical

characteristics• accessible population: geographic and

temporal characteristics

outcome research 9

Primary data: subjectsPrimary data: subjects• Exclusion criteria: be parsimonious

– highly likely of being lost to follow-up– inability to provide good data– ethical barriers– refusal– etc.

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Primary data: subjectsPrimary data: subjects• Sampling

– probability sampling: *often used in PH studies• simple random• systematic• proportion to population size (PPS)• stratified random• cluster

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Primary data: subjectsPrimary data: subjects• Sampling

– non-probability sampling• consecutive *most often used in clinical

studies• convenience• judgmental

• Actual subjects– non-response ‘bias’ and its prevention– systematic error/internal validity

outcome research 12

Primary data: measurementPrimary data: measurement• Measurement scale

– categorical (nominal) including binary– ordinal or rank– interval or continuous

• Choose proper scale and instrument

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Primary data: measurementPrimary data: measurement• Precision

– free of random error

• Accuracy– free of systematic error

• Validity of the instrument vs. internal validity of the study

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Primary data: measurementPrimary data: measurement• Precision: free of random error

– the degree to which a variable has nearly the same value when measured several times

– coefficient of variation (C.V.)– reliability

• test-retest• internal consistency• inter- and intra-observer consistency

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Primary data: measurementPrimary data: measurement• Accuracy: free of systematic error

– the degree to which a variable actually represent what it is supposed to represent

– validity– with gold standard

• sensitivity• specificity• predictive validity

outcome research 16

Primary data: measurementPrimary data: measurement• Accuracy: free of systematic error

– without gold standard• face validity & content validity• criterion-related validity

– convergence validity– divergence validity

• construct validity

outcome research 17

Primary data: measurementPrimary data: measurement• Choice of proper instrument

– Status or time to event:• binary/nominal• registry/clinical or other records• classified from interval scale

– Surrogate endpoint:• nominal/ordinal/interval• from clinical or laboratory instruments

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Primary data: measurementPrimary data: measurement• Choice of proper instrument

– quality of life– functional status– satisfaction– cost

• interval scale• questionnaires• clinical or financial records

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Primary data: measurementPrimary data: measurement• General rules of increasing precision

– standardization of methods– training and certifying observers– refining the instrument– automating the instrument– repeating the measurements

outcome research 20

Primary data: measurementPrimary data: measurement• General rules of increasing accuracy

– the same as that for precision except repeated measurements

– making un-obstructive measurements– blinding– calibrating the instruments

outcome research 21

Primary data: measurementPrimary data: measurement• Questionnaire

– use existing vs. self-designed ones– copyright and translation right– standardized translation procedure

• forward• backward• pilot and field validation testing

outcome research 22

Primary data: measurementPrimary data: measurement• Questionnaire design

– questions: open vs. closed-ended– format/wording

• clarity• simplicity• neutrality• specific• time-frame

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Primary data: measurementPrimary data: measurement• Questionnaire design

– Scale• summative (Likert)• cumulative (Guttman)

– Draft and content or face validity examination

– Coding/precoding– Pretest and revision, reliability and validity

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Primary data: measurementPrimary data: measurement• Questionnaire use

– Administration• interview: face-to-face, group interview,

telephone• self-administered: concurrent, mailed,

internet

– Quality control

• Data management• Report writing

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Primary data: ethical Primary data: ethical concernsconcerns

• Subjects– four principles of medical ethics:

• autonomy• beneficience• non-maleficence• justice

– informed consent/not limited to experimental studies/IRB: institutional review board• Special conditions

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Primary data: ethical Primary data: ethical concernsconcerns

• Subjects source– institutions/physicians

• Cooperation/collaboration– right and duty– authorship

• Instruments– copyright and citation

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Secondary data: overviewSecondary data: overview• Strengths

– speed: especially easy in the e-era– economy

• Weakness– quality unsure– needed information not accessible

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Secondary data: typesSecondary data: types– Aggregate: group as unit

• vital statistics• disease incidence/prevalence of geographic area• economic, demographic, … data/census

– ecological correlation study/ecological fallacy

– Individual: individual as unit• government statistics: mortality, cancer registry, ...• hospital discharge data/health insurance data, ...• previous studies of different purposes

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Secondary data: how to Secondary data: how to startstart

– Find data bases to fit a research question• choose a research question/literature review• list predictors/outcome variables• identify proper data bases that might include

the variables• be familiar with the data bases/consultation• choose the best one/application• formulate hypotheses and statistical methods• data analysis

outcome research 30

Secondary data: how to Secondary data: how to startstart

– Find research questions to fit existing data sets:• the reverse way of usual research design• choose (a) data base(s)/application• be familiar with the data bases/make a flow

sheet of variables/identify pairs/groups of variables of interest

• literature review/experts consultation• formulate hypotheses and statistical methods• data analysis

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Secondary data: data Secondary data: data linkagelinkage

• Making use of more than one data bases

• Key linkage variable:– a variable that all the data bases possess– e.g. individual citizen’s ID– easy in electronic data bases

• Enrich the ‘utility’ of data– e.g. hospital discharge data --- mortality

registry-- survival of a certain disease

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Secondary data: Secondary data: Public accessible Public accessible secondary data bases in Taiwansecondary data bases in Taiwan

– aggregate data: national and local•內政部台閩地區人口統計•衛生署衛生統計•其他政府出版品集體統計資料

– individual data:• mortality (death certificate) registry 死亡檔 (origi

nal ID)• cancer registry 癌登檔 (ID removed after linkage)• National Health Insurance data base (scrambled I

D) 全民健保資料庫

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Secondary data: Secondary data: Public accessible Public accessible secondary data bases in Taiwansecondary data bases in Taiwan

– individual data: previous studies•中研院調查研究工作室學術研究資料庫

– 台灣地區社會變遷基本調查– 政大選舉中心選舉調查– 國民營養狀況變遷調查 等

• Individual-based government surveys– 生育力調查– 收支調查– 戶口普查 等

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Secondary data: pSecondary data: public inaccessible ublic inaccessible secondary data bases in Taiwansecondary data bases in Taiwan

• NHI original data (ID not scrambled)• Household registry data• Health station-household data: PHIS• Military service data• Tax data, ...

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Secondary data: hospital-based Secondary data: hospital-based data ready for clinical researchdata ready for clinical research

• Data kept by separate hospitals– computerized

• hospital cancer registry• hospital NHI claims data• other computerized records

– not computerized• written form on medical records• special tests/examinations/studies

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Secondary data: other Secondary data: other countriescountries

– US • government-owned• separate health insurance, managed

care, HMOs

– Scandinavian countries• large and detailed medical and national

files with original ID, ready to link

– Germany• not accessible due to historical reasons

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Secondary data: ethical concerns Secondary data: ethical concerns and related limitationsand related limitations

– Protection of privacy/confidentiality• personal electronic data protection law• scrambled ID: NHI data base

– inaccessible to original record/individual, unable to examine validity of data or improve quality

– data bases linkage impossible: poverty of contents

• third party linkage/removal of ID before use: cancer registry

• researcher/investigator agreement: hospitals• informed consent: certain studies/hospitals

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Secondary data: ethical concerns Secondary data: ethical concerns and related limitationsand related limitations

– Ownership and intelligence property• government and public data bases• individual researcher/investigators

– data donation– data share– authorship– commercialization of data

outcome research 39

‘‘Tertiary data’Tertiary data’• Pooling projects

– after publication: meta-analysis– before publication or to use unpublished

raw data