Week 1 - Research Designs in Nutrition

Outcome

Health condition, physiological effect, or disease of interest.

Exposure

Dietary factor believed to be associated with an outcome.

Association

Relationship between exposure and outcome, classified as positive or negative.

Confounder

Factor that distorts the interpretation of an association between exposure and outcome.

Experimental Research Design

Strategically designed interventions to assess a causal relationship between diet and disease. Strength: Establishes causality. Limitation: High cost and complexity.

Epidemiological Research Design

Observational investigations to examine how disease rates vary among population groups. Strength: Useful for generating hypotheses. Limitation: Susceptible to confounding.

Laboratory Studies

Tightly controlled experiments on cells, molecules, or animals to test specific variables. Strength: High precision and control. Limitation: Lacks human applicability.

Cross-Sectional Studies

Observational studies where exposure and outcome are measured at the same point in time. Strength: Fast and cost-effective. Limitation: Cannot establish temporal sequence.

Case-Control Studies

Studies comparing a diseased group (cases) with a healthy group (controls) to examine past diet. Strength: Efficient for rare outcomes. Limitation: Subject to recall bias.

Recall Bias

Error where participants with a disease remember or report past dietary intake differently.

Odds Ratio (OR)

Statistical measure comparing odds of disease in an exposed group versus an unexposed group.

OR Interpretation (>1)

Indicates a positive association and an increased risk among those exposed.

OR Interpretation (<1)

Indicates an inverse, protective association and a decreased risk among those exposed.

Cohort Studies

Prospective studies following a healthy group over time to see who develops an outcome. Strength: Establishes temporal relationship. Limitation: Loss to follow-up over time.

Relative Risk (RR)

Statistical measure comparing risk of an outcome in an exposed group versus an unexposed group.

Hazard Ratio (HR)

Statistical measure of the chance of an exposure being associated with an outcome group over time.

Confidence Interval (CI)

Range indicating the level of confidence in a statistical measure and whether findings are meaningful.

CI Non-Meaningful Threshold

If the confidence interval range crosses 1, the finding is not meaningful.

Human Intervention Trial / RCT

Experimental study where participants are allocated to an intervention or control group. Strength: Gold standard for causality. Limitation: Ethical limitations and high cost.

p-value

Measure of the probability that an observed effect is due to the intervention rather than chance.

Statistically Significant p-value

A p-value of less than 0.05 generally indicates a meaningful effect.

Case Group

The group of participants in a study who possess the health condition, disease, or outcome of interest.

Control Group

The group of participants in a study who do not have the health condition or disease, serving as a comparison baseline.