Lecture 2:epidemiology study design

Question 1

Where is the strongest method of scientific evidence located in the pyramid ?

Answer 1

At the top

Example: Meta Analysis

Question 2

Where is the weakest method of scientific evidence located in the pyramid?

Answer 2

Bottom

Example: expert opinion, case series

Question 3

What is the order of the pyramid of hierarchy of scientific evidence?

Answer 3

Meta analysis 
Systematic review 
Randomised controlled trials 
Cohort studies 
Case control studies 
Case series/case reports
Background information/ expert opinion

Question 4

How can validity be described?

Answer 4

Measurement validity
Study validity
Internal validity
External validity

Question 5

What is measurement validity?

Answer 5

The degree to which a measurement measures what it purports to measure

Question 6

What is study validity ?

Answer 6

The degree to which the inference draw from a study is warranted

Question 7

What is internal validity ?

Answer 7

Groups used for comparison are selected and compared in such a manner that observed differences between them in terms of dependent variable under study, apart from sampling error, can be attributed only to the hypothesised effect under investigation

Question 8

What is external validity ?

Answer 8

Generalisability. A study has good external validity if it can produce unbiased inferences regarding a target population (beyond the study participants)

Question 9

Factors of descriptive studies ?

Answer 9

No comparison
Bottom of pyramid
Important role in medical sciences
Evidence generated from clinical observation

Question 10

What is cohort studies?

Answer 10

An observational method in Epidemiology, whereby a population is defined at To and is followed up over a period of time, sometimes over ,any years, and exposures and health outcomes of interest remains recorded

Question 11

What are synonyms of cohort studies?

Answer 11

Longitudinal studies

Prospective studies

Question 12

What are the pros of cohort study?

Answer 12

Sufficient large follow up

Question 13

What are the cons of cohort study ?

Answer 13

• lack of control over the groups within the population

- key exposures of interest may go hand-in-hand with confounding factors

Question 14

What are case control studies?

Answer 14

Retrospective observational studies, they stariate the END POINT and look BACKWARDS to record historical differences in exposure between two or more groups (I.e. cases)

Question 15

What are the pros of case-control studies?

Answer 15

Make it possible to study the different exposures that may have lead to rare conditions

Suited for study of rare conditions

Suited for historical well documented exposes

Question 16

What are cons of case-control studies?

Answer 16

Open to a number of biases

Question 17

What is a Caveat?

Answer 17

An association between a risk factor and a disease

DOES NOT NECESSARILY INDICARE A CASUAL RELATIONSHIP

Question 18

What are cross-sectional studies?

Answer 18

Observational method in epidemiology that represent a SNAPSHOT of the health picture in a population at a given point in time

Question 19

What are the pros of cross sectional studies?

Answer 19

Useful for estimating prevalence within a population

Question 20

What is the study design temporal direction of cohort study?

Answer 20

From exposure to outcome

Question 21

What is the study design temporal direction of case-control study?

Answer 21

From outcome to exposure

Question 22

What are randomised controlled trials?

Answer 22

An experimental method in Epidemiology, where participants wishing a population are randomly allocated to two or more groups called INTERVENTION/EXPERIMENTAL groups/ CONTROL groups

Question 23

What is usually considered the gold standard in terms of hypothesis testing?

Answer 23

High quality Randomised controlled trials

Question 24

What are the pros of Randomised controlled trials?

Answer 24

Internal validity : minimises confounding bias
Replicability
External validity: generalisability
More likely to influence practice

Question 25

What are the cons of Randomised controlled trials?

Answer 25

``` Coverage bias Participation bias Can’t answer all question types Expensive Context- free ```

Question 26

When does Confounding occur?

Answer 26

Confounding occurs when the effects of two associated exposures have not been separated, resulting in the interpretation that the effect is due to one variable rather than the other

Question 27

What is the consequence of Confounding?

Answer 27

The consequence is that the estimated association is not the same as the true effect

Question 28

...........study design answer............types of questions

Answer 28

Different | Different

Question 29

What is qualitative research?

Answer 29

Any type of research that employs non-numerical information to explore individual or group characteristics, producing findings not arrived at by statistical procedure or other quantitative means (attitudes,acceptability,value,ethics,etc)

Question 30

What factors must you consider in choosing the appropriate method ?

Answer 30

Outcomes measures: qualitative or quantitative? Valid and reliable? How can they be operationalised? Duration: over what period of time will outcomes manifest themselves Controlling variables: how can the effects of extraneous aria let’s be minimised?

Question 31

What is meta-analysis?

Answer 31

Pooling results in a statistically valid fashion

Question 32

What is systematic review?

Answer 32

Identifying, quality appraising and synthesising ALL published information in a giving clinical area

Question 33

All epidemiological studies must be reviewed and approved by ethical review committees True or false

Answer 33

True

Question 34

What are the ethical principles that apply to epidemiological practice and research?

Answer 34

Informed consent Confidentiality Respect for human rights Scientific integrity

Question 35

Epidemiological research methods can be used to answer questions regarding Clinical and Public Health risk factors and interventions. True or false

Answer 35

True

Question 36

Randomised Controlled Trials are usually considered the ‘gold standard’, especially for testing interventions, AND they’re not always feasible or ethical True or false

Answer 36

False

Question 37

A study of any design is likely to have a range of strengths and weaknesses. True or false

Answer 37

True

Question 38

Qualitative methods may be used to gain in-depth data about attitudes, and quantitative data are not normally required for hypothesis testing True or false

Answer 38

False