Research Design and Methods

Question 1

What is the purpose of Research design?

Answer 1

refers to the research plan used to answer the question under consideration

-The research design is chosen based on the question

Question 2

What defines the accuracy of study results?

Answer 2

Validity

The more a design refers to the question of the study the more valid the study is

Question 3

Internal Validity

Answer 3

The extent to which a clinical outcome (dependent variable) is caused by the treatment (independent variable)

How valid are the methods to answer the question

Question 4

What are the dependent and independent variables?

Answer 4

Dependent: Often the outcome (outcome measure) -> depends on the independent variable

Independent: We are trying to determine the outcome of the independent variable: disease or treatment
-> It influences the dependent variable and drives the outcome

Question 5

External Validity

Answer 5

Application of the results to the broad population -> Can the study be replicated in other situations?

Question 6

What factors may reduce internal validity?

Answer 6

-Confounding variables: a third variable that has an effect on the two I am interested in and messes up the results - f.e. LDL indicated heart disease -> confounding variable would be smoking, hypertension (it increases heart disease as an independent variable)

-Chance/coincident findings

Question 7

How to determine if a study has external validity

Answer 7

Is the study repeatable in other populations?

Question 8

How might a researcher maximize
external validity?

Answer 8

Choose participants from different populations in different countries with similar lifestyles, and behaviors, … f.e. Western countries

Question 9

What is Correlation?

Answer 9

Two variables are related or correlated -> it does NOT mean that X causes Y

Question 10

What is an association?

Answer 10

-If X looks like it is related to Y = Association, Correlation

-BUT Association is not equal to Causation

Question 11

What are the criteria to prove a cause-and-effect relationship = Causality?

Answer 11

Criteria by Sir Austin Bradford Hill (1965)
-Temporality (time-related f.e. taking antihypertensive and feeling deezy an hour later due to low BP)
-Strength (higher dose - higher effect - similar increase in all curves on the graph)
-Biologic Gradient (similar to strength)
-Consistency (effect happens over and over again)
-Specificity (happens with a specific drug)
-Plausibility (antihypertensive drug lowers BP)
-Coherent (same effect in animals?)
-Analogy (similar drug class with similar effects)
-Experiment (experimental evidence)

Question 12

What are spurious relationships?

Answer 12

a mathematical relationship where two variables have no causal connection but they look as if they have -> due to coincidence or a third factor (confounding factor or variable)

Question 13

What is the difference between descriptive and analytical studies?

Answer 13

What is the purpose? Just describing or testing a hypothesis

Descriptive: just describing information about a disease or event without intervening

Analytical: trying to understand the relationship or causal mechanism between 2 or more variables

Question 14

What are factors that help to describe effects in a descriptive study?

Answer 14

Who?
What?
Where?
When?
Why?

Question 15

What are study designs based on Time Orientation?

Answer 15

-Prospective (takes longer, more expensive)

-Retrospective (often medical records, faster, cheaper)

Question 16

What are study designs based on Experimental Setting?

Answer 16

-Randomized Controlled Trial (required by FDA, gold standard for safety and efficacy, ALWAYS prospective)

Experimental Design: The researcher controls the treatment (independent variable) through randomization

-Observational (observing a relationship between two variables, not randomized)

Question 17

What are the Observational studies?

Answer 17

-Case Report - Single Case
-Case Series - Study of multiple similar cases
-> very weak evidence
->used to uncover relationships that can be further explored

-Cross-sectional studies
-Case-control studies
-Cohort studies

Question 18

What is a Cross-sectional study?

Answer 18

-Examine population characteristics at one point in
time (a cross-section)
-presents a snapshot of the exposure status/outcome

Question 19

Why do Cross-section studies cant explain causation?

Answer 19

Because exposure and outcome are measured at the same time

Question 20

Which study is used to determine prevalence (proportion of population with a given characteristic in a time period)?

Answer 20

-Cross-sectional studies

Question 21

What are Case-Control studies?

Answer 21

Comparing two groups - one with the disease/outcome and one without and tracking back to look for the exposure (retrospective)

-Case group AND Control group share same characteristics EXCEPT of the disease

Question 22

What types of diseases are investigated with Case-control studies?

Answer 22

Rare diseases, where it takes time between exposure and the outcome

Question 23

What are cohort studies?

Answer 23

-Two groups (exposed and unexposed - both don’t have the disease) are followed for a period of time until the development of the disease

Question 24

What are cohort studies used for?

Answer 24

-Determine the incidence (number of cases) in the exposed vs. unexposed group

-Exposure causes outcome -> cohort studies can be used to study CAUSATION

Question 25

What is a way to prove causality in an experimental study?

Answer 25

-Randomization
-varying dose
-Blindfolding

Question 26

Are RCTs prospective or retrospective?

Answer 26

ALWAYS Prospective

Question 27

What is the disadvantage of not having a randomized study?

Answer 27

variables and participants are self-selected -> opens room for confounding factor