Association & Causation in Epidemiological Studies Quiz

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Questions and Answers

What is the purpose of the 'comparison' in the final proof process?

To measure the extent of association, effect, or risk (correct)

To establish a cause and effect relationship

To determine if the study methods are accurate

To suggest additional studies using large sample sizes

What is the significance of Step 1 in establishing an 'exposure - outcome' relationship?

Conducting hypothesis testing

Determining statistical significance

Ensuring the accuracy of study results and avoiding spurious findings (correct)

Evaluating indirect relationships with confounders

If a study has a non-significant p-value, what is one possible reason ?

Inclusion of strong confounders

Low power of the study (small sample size) (correct)

High power of the study

Overestimation of the study results

What should an investigator consider if the 'exposure - outcome' association is statistically significant?

Evaluate if the relationship is due to a third variable (confounder) Signup and view all the answers

What is suggested if the exposure-outcome association is not statistically significant?

Use meta-analysis to explore the relationship further Signup and view all the answers

'Validity, reliability, and bias' are factors considered in which step of establishing an exposure - outcome relationship?

Step 1 Signup and view all the answers

Which type of association is exemplified by the relationship between shoe size and reading performance in elementary school children?

Spurious association Signup and view all the answers

What is the main purpose of a 'comparison' in observational studies when evaluating associations?

To generate a summary measure of association or risk Signup and view all the answers

In the context of epidemiological studies, what does it mean when we hypothesize that a factor 'may have a role in etiology'?

The factor is a probable contributor to the development of the disease Signup and view all the answers

Which statistical measures are commonly used as the extent of 'Association' or 'Effect' in observational studies?

Risk Ratio (RR) and Odds Ratio (OR) Signup and view all the answers

When evaluating a potential causal relationship between two factors in epidemiology, what should be emphasized before drawing conclusions?

Considering confounding variables and biases Signup and view all the answers

What is the first question that must be asked when an association is observed?

Is it real? Signup and view all the answers

How is bias defined in the context of a study?

A systematic error leading to a mistaken estimate of the exposure's effect Signup and view all the answers

Why is bias considered a systematic error?

Because once introduced, it cannot be fixed Signup and view all the answers

What is the impact of bias on the estimate of an exposure's effect?

Results in an estimate either above or below the true value Signup and view all the answers

How do alternative explanations like bias and confounding affect study results?

They may lead to spurious results Signup and view all the answers

When observing an association, what might bias or confounding lead researchers to falsely conclude?

Presence of a valid association when there isn't one Signup and view all the answers

Study Notes

Bias and Confounding

Bias is a systematic error in the design, conduct, or analysis of a study that results in a mistaken estimate of an exposure's effect on the risk of disease.
Bias can produce spurious results, leading to conclusions of a valid statistical association when none exists or vice versa.
The effect of bias will be an estimate either above or below the true value.

Establishing a Cause & Effect Relationship

The process of establishing a cause & effect relationship involves a sequence of steps.
Step 1: Ensure the results of the study are accurate and not spurious, considering correct methods, validity, reliability, and bias.
Step 2a: Determine if statistical results indicate an association, using p-value and 95% CI.
Step 2b: If not significant, consider the possibility of low power due to a small sample size, and suggest additional studies or meta-analysis.
Step 3: Evaluate if the relationship is due to an indirect relationship with a third variable (confounder).
Step 4: If the confounder is excluded, test the postulated causal relationship on the criteria of causal association.

Association and Causation

Association is the concurrence of two variables more often than would be expected by chance.
Types of associations include spurious, indirect, direct (causal), one-to-one causal, and multi-factorial causal.
Observing an association does not necessarily imply causation; a comparison is required to establish a causal relationship.

Examples of Association and Causation

High serum homocysteine levels may be associated with an increased risk of IHD, but further comparison is needed to establish a causal relationship.
The presence of Helicobacter pylori may be associated with duodenal ulcers, but further comparison is needed to establish a causal relationship.

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Description

Test your knowledge on the concepts of association and causation in epidemiological studies, as discussed by Dr. Sireen Alkhaldi in the field of community medicine for the academic years 2023/2024 at the School of Medicine, The University of Jordan.