Research Methodology Flashcards
Advantages of a Descriptive Study
Hypothesis generation
Health service planning & management
Describe descriptive study.
No comparison group. Answers who, what, when, where.
The disadvantage of a Descriptive Study
Cannot establish causality
Describe a cross-sectional study
Exposure and outcome measured at one point in time
= snap-shot
= prevalence study
Advantages of a Cross-sectional study
Relatively cheap & easy
Measure multiple variables at the same time
Disadvantages of a Cross-sectional study.
Cannot measure temporality
Cannot measure incidence
Information bias (recall bias); Selection bias
How is a cross-sectional study conducted?
Gather information regarding both the presence of a disease and an individual’s exposure status, while simultaneously collecting data on the outcome of interest and exposure status.
Describe a Cohort Study.
Cohort : “A group of people who share a common characteristic or experience within a defined period”.
Advantages of a Cohort Study
Temporality
Can calculate incidence
Useful for rare exposures
Can study multiple outcomes (of single exposure)
Disadvantages of a Cohort study.
Loss-to-follow-up
Detection bias
Time consuming, expensive
How is a cohort study conducted.
Get a sample population without the disease and then divide into groups that are exposed and not exposed and record outcomes.
Compare Prospective and Retrospective studies.
Retrospective: Study begins when outcome has already occurred
Participants grouped on exposure (NOT outcome status)
Prospective: Outcome has not yet occurred
Participants grouped on basis of exposure
Follow up to see if outcome occurs
Describe a case-control study.
Identify cases (those who have the outcome/disease)
Choose controls (those without outcome/disease)
Measure exposure in both cases and controls
Common sources hospital, neighbourhood, family members. “Matched controls”
Advantages of the case-control study
Efficient
Relatively quick
Good for rare outcomes
Disadvantages of a Case control
Selection bias (selection of controls)
Information bias: Recall
Can only calculate odds ratio
No temporality
How do we conduct a case control study?
From a population select Cases(Diseased) and Controls (No disease)- Controls need to represent the source population that gave rise to the disease. Thereafter divide each category into exposed and unexposed.
Describe RC study.
Similar to cohort, but exposure
assigned randomly & always prospective
Advantages of a RC study
Minimal bias/confounding-Participants have equal chance of receiving exposure/intervention as the control.
Strong evidence
Disadvantages of a RC study
Ethical issues
Time-consuming, expensive
Loss-to-follow-up
Not suitable for all research questions
Compare Blinding and Allocation concealment
Allocation concealment refers to the process of hiding or concealing the method used to assign treatments or interventions to participants in a research study. This ensures that neither the patients nor the clinicians/investigators know which treatment the participant will receive before they are enrolled in the study. The purpose of allocation concealment is to prevent bias in treatment assignment, ensuring that the groups being compared are comparable in terms of baseline characteristics.
Blinding, on the other hand, is a technique used to prevent bias in the assessment of outcomes during a study. It involves keeping the participants, healthcare providers, researchers, or outcome assessors unaware of the treatment group assignments. Blinding ensures that any differences observed in outcomes between treatment groups are not influenced by knowledge of the assigned treatment. There are different types of blinding, such as single-blind (where either the participant or the assessor is unaware of the treatment) and double-blind (where both the participant and the assessor are unaware).
Describe Ecological studies.
Work with population or group-level variables. Previous examples were all looking at individual level. Study design itself can vary: but mostly cross-sectional ecological study
Advantages of a Ecological study
Hypothesis generation
Relatively quick and cheap
Disadvantages of an ecological study
Ecological fallacy – see next slide
Confounding, bias
Cannot determine causality
Describe ecological fallacy.
The bias that may occur because an association observed between variables on an aggregate level does not necessarily represent the association that exists at an individual level” .
Ecological fallacy is the assumption that associations found at the group level apply to individuals
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