Study design

Question 1

Prospective study

Answer 1

-subjects exposed to a risk factor or intervention are assembled and then the researcher waits for the outcome to take place

Question 2

Retrospective study

Answer 2

-a group of individuals has been assembled because they have already experienced the exposure in question

Question 3

Descriptive studies

Answer 3

• aim to describe the characteristics of a group of subjects
• there is no testing of a causal hypothesis or any comparisons with other groups
• describe the characteristics of members of the study group and discuss the distribution of these characteristics

Question 4

Examples of descriptive studies

Answer 4

• Case reports and case series

- Cross-sectional studies

Question 5

Cross sectional studies

Answer 5

• can suggest the presence of putative relationships among variables
• also called prevalence studies
• describe various attributes of the subject in a study group but at a single point in time (a snapshot)
• surveys and census

Question 6

Prospective longitudinal studies

Answer 6

• observations are repeated in the same population over a prolonged time
• this helps to study the natural course of illness, study risk factors and find out incidence rates
• very expensive and time consuming

Question 7

Analytical studies

Answer 7

• involve comparative analysis of two groups to measure the association between variables of interest e.g disease and a risk factor
• e.g case control studies and cohort studies

Question 8

Example of analytical studies

Answer 8

• case control studies
• cohort studies
• ecological studies

Question 9

Analytical studies

Answer 9

-involves a comparative analysis of two groups to measure the association between variables of interest

Question 10

Case Control study

Answer 10

• the researcher assembles a group of subjects, some of whom have already experienced an outcome (cases) and others who have not (controls)
• the researcher then estimates the proportion in each group who have experienced the exposure of interest

Question 11

Cohort study

Answer 11

-an observational study of a group of people with specified characteristics or exposure who are followed over a period of time to detect events/outcome

Question 12

Ecological study

Answer 12

• special type of analyical study
• data is gathered to describe what happens in a group rather than the individual
• makes assumptions about populations- ecological fallacy

Question 13

Experimental studies

Answer 13

• generally prospective cohort studies where the exposure is experimentally assigned to the groups in a variable fashion to observe the effect
• clinical trials are experimental studies or interventional studies

Question 14

Cross sectional study example

Answer 14

• how common is a condition?

- what is the nature of this sample?

Question 15

Case Control study

Answer 15

-what are the causes of this outcome?

Question 16

Cohort study

Answer 16

-What are the effects of this risk factor/exposure?

Question 17

Interventional study

Answer 17

-what is the effect of this intervention?

Question 18

Treatment effectiveness

Answer 18

-pragmatic RCT or systematic review

Question 19

Treatment efficacy

Answer 19

-experimental RCT or systematic reviews

Question 20

Causation

Answer 20

-cohort or case control

Question 21

Prognosis

Answer 21

cohort

Question 22

Diagnostic assessment using a new tool

Answer 22

-cross-sectional comparison to gold standard

Question 23

Health economics

Answer 23

-cost effectiveness study

Question 24

‘Meaning’ or health ‘experience’

Answer 24

-qualitative studies