Timed Essay

Question 1

What is epidemiological bias?

Answer 1

Systematic error in design, analysis or interpretation that leads to inaccurate conclusions.

Question 2

What is selection bias?

Answer 2

Systematic difference between the characteristics of the participants and the population, an inaccurate representation.

Question 3

What is information bias?

Answer 3

Error in measurements of exposure, outcomes or confounding.

Question 4

What is confounding?

Answer 4

When a third factor influences the observed relationship between exposure and outcome leading to an incorrect interpretation of the association.

Question 5

What is Simpson’s paradox?

Answer 5

A correlation present between may disappear or are reversed when the groups are recombined

Question 6

What statistical test can be done to assess bias or confounding?

Answer 6

Chi-squared

T-test

Logistical regression

Sensitivity analysis

Subgroup analysis

Question 7

What is sensitivity analysis?

Answer 7

Changes in study factors or assumptions can influence the results.

Question 8

What is subgroup analysis?

Answer 8

How small changes between group in population affect the outcome

Question 9

What is chi-squared?

Answer 9

Association in of categorical data.

Whether the observed and expected values have a difference which is significant and not due to chance.

Question 10

What is a t-test?

Answer 10

Association of continuous data.

Compare 2 groups and see if the observed differences are significant.

Question 11

What is logistic regression?

Answer 11

Used to adjust for confounding variables.

Studies how changing variables will change the outcome of a binary event.

Question 12

Outline the main points of the self-reported shift work and belief on cancer causation.

Answer 12

Participants were given a questionnaire on whether they believed that shift work patterns caused cancer.

Then they were asked to self-report their work shifts.

This was compared to their actual shift patterns

This was to test whether belief affected the way they recalled, the likelihood of them getting cancer or recall changing belief.

A significant association between belief and recall bias.

No proof to show recall changed belief.

Question 13

Outline the study on biomarkers in bias and confounding?

Answer 13

Strengthen the statistical association

Reduce random error

Increase bias and confounding due to often being used in a small sample size.

This is because biomarkers can be both exposure and outcome.

Question 14

Outline the meta-analysis on bias and confounding in IBD studies.

Answer 14

A random sampling of 160 observational studies.

67/160 Confounding

89/160 Bias

Reporting the issues in discussion was very low.

Question 15

Outline the recall bias study done on alcohol consumption before an injury among emergency department patients.

Answer 15

Reporting drinking for the same 6-hour period every day going back a week.

Vancouver and Victoria

Estimate drinking frequency and heaviness.

3 days less biased after that accuracy decrease drastically.

Question 16

Outline information bias in gynaecological studies.

Answer 16

Misclassification is unmatched for the exposed and unexposed.

Confounders unmeasured and unmatched.

Leads to bias in public health.

Question 17

What do longitudinal rely on?

Answer 17

Commitment of the participants at the start as in the follow up.

Question 18

What is covariates?

Answer 18

Joint variability for 2 variables

Question 19

What is a validation study?

Answer 19

Assess the validity of a test or instrument.

Question 20

What is a calibration equation?

Answer 20

Compares the measured values of an instrument to the standard allowing to correct any mistakes.

Question 21

Meta-analysis of the association of vaccines and autism.

Answer 21

Not associated.

5 case-controlled and 5 cohort.

Report published in 1998.

Massout break in 2019 in the US.

Parental anxiety and public panic.

Cost of outbreak control and changing public beliefs.

Question 22

How to encourage correct influence on public health?

Answer 22

Encourage collaboration

Regular monitoring to account for emerging bias.

Transparent reporting

Peer review

Question 23

What can happen when epidemiological studies are in correct on public health?

Answer 23

Incorrect diagnosis and intervention, which can be dangerous and expensive.

Question 24

What is the definition of reliability?

Answer 24

Refers to the consistency.

Measurement to produce similar results under different conditions over time.

Question 25

What is the definition of validity?

Answer 25

The extent to which a test or measurement accurately assesses what it is intended to do.

Question 26

What are the epidemiological failures?

Answer 26

Inaccurate data collection

Insufficient surveillance

Misinterpretation of findings

Question 27

How are bias and confounding interlinked?

Answer 27

Overlap in definitions

Interconnected causes

Shared methodological challenges

Mutual influence on accuracy

Question 28

How do bias and confounding differ in time of occurance?

Answer 28

Bias occurs during the carrying out of the study.

Confounding usually occurs after exposure during measurement.

Question 29

How do bias and confounding differ in origins of influence?

Answer 29

Bias from flaws of study design.

Confounding from the presence of a 3rd variable.

Question 30

How do bias and confounding differ in their impact on association?

Answer 30

Bias alters the observed association.

Confounding creates a false association.

Question 31

How do bias and confounding differ in addressability?

Answer 31

Bias can be addressed during study design.

Confounding can be constantly addressed during data analysis.

Question 32

How do bias and confounding differ due to association direction?

Answer 32

Bias can make the association more extreme.

Confounding creates a false association all together.