Lecture 7, part 2

Question 1

What are sources of exposure info?

Answer 1

Pre-existing records
Self-report
Physical/biological observations

Question 2

Examples of pre-existing records

Answer 2

Medical records
Insurance records
Employment records
Vital stats
Tax or property records

Question 3

Advantages of pre-existing records

Answer 3

Inexpensive
Relatively easy to work with
Usually unbiased since data were collected for non-study purposes

Question 4

Disadvantages of pre-existing records

Answer 4

Exposure info may not be precise enough to address the research question
Records frequently do not contain data on potentially confounding factors

Question 5

Examples of self-report

Answer 5

Interviews
Surveys
Diaries

Question 6

Advantages of self-report

Answer 6

Opportunity to question subjects on as many factors as necessary
Good for collecting info on exposures not routinely recorded

Question 7

Disadvantages of self-report

Answer 7

Rely on participants’ ability to know and recall info
Potential response bias due to stigma, response expectations, observation, etc.
Participants may not be sufficiently aware of their exposure status

Question 8

Examples of physical/biological observations

Answer 8

Physical exams
Lab tests of biological specimens
Environmental monitoring

Question 9

Advantages of physical/biological observations

Answer 9

Biomarkers of exposure often more objective
Allow ascertainment of internal dose/exposure
Higher quality data

Question 10

Disadvantages of physical/biological observation

Answer 10

Can be invasive and expensive to collect
Appropriate lab tests may not be available
May be subject to bias if interpretation or clinical observation is influenced by exposure

Question 11

______of the exposure is crucially important

Answer 11

Timing

Question 12

Relevant etiologic period defintion

Answer 12

Time during which an exposure will affect dz occurrence

Question 13

How should study design be grounded?

Answer 13

In knowledge of natural hx of dz as well as hypothesized biological mechanism

Question 14

What should be considered in terms of f/u?

Answer 14

Length required to observe the outcome of interest

Question 15

Induction period definition

Answer 15

Interval between causal action and dz initiation

Question 16

Latent period definition

Answer 16

Interval between dz onset and detection

Question 17

What should be considered to determine the length of f/u?

Answer 17

Minimum latency
Maximum latency

Question 18

Minimum latency considerations

Answer 18

How soon can dz result after exposure has first occurred

Question 19

Maximum latency considerations

Answer 19

Once exposure has ceased, when does the alteration in risk disappear (if at all?)

Question 20

Characteristics of good measurement of outcome

Answer 20

Should be as precise and objective as possible

Question 21

What types of measurements of outcome are possible?

Answer 21

Categorical
Continuous
Dichotomous

Question 22

What should be be done in measuring outcome when the measures are weaker/more subjective?

Answer 22

Use triangulation, or supplement

Question 23

Sources of outcome data

Answer 23

Self-report
Employee records
Medical/pharmacy/insurance records
Physical exams/blood testing
Death or dz registries
Multiple sources

Question 24

Definition of information bias

Answer 24

Systematic error in the measurement of the exposure and/or outcome

Question 25

Key characteristics of information bias

Answer 25

Occurs after participants have entered study
Pertains to how data are collected
Can bias results away or toward the null
Can occur in any type of study design

Question 26

What is the most common type of information bias?

Answer 26

Misclassification bias