week four

Question 1

What are the types of experimental studies

Answer 1

RCT
Field Trials
Community trials

Question 2

What is an RCT

Answer 2

• An RCT is an experimental comparative study in which participants are allocated to treatment/intervention or control/placebo groups using a random mechanism
• Participants have an equal chance of being allocated to an intervention or control group

Question 3

Advantages of RCT

Answer 3

• RCTs are the ‘gold standard’ epidemiological studies
• Less risk of bias and confounding than any other epidemiological study
• Provide strong evidence of causal relationships
• Can be used to study multiple outcomes
• Measure the incidence rate of an outcome

Question 4

Disadvantages of RCT

Answer 4

• Often expensive
• Require large study group (multiple sites)
• Long follow-up period
• Ethical issues
• Generalisability needs to be carefully assessed – can we generalise these to the broader population

Question 5

Field Trials

Answer 5

Trials in the ‘field’
Aimed at disease-free people in the population. These people do not have the disease but are at risk
Evaluate interventions at reducing exposure

Preventive studies, evaluating prevention strategies
i.e. sunscreen, shade policies at schools, smoke free areas

Question 6

Community/Cluster Trials

Answer 6

The treatment groups are communities rather than individuals

They are for treatments you cannot deliver individually e.g. flu vaccination, fluoridated water

Question 7

What is the evidence bases pyramids structure (least to most bias)

Answer 7

systematic reviews 
RCT 
cohort studies 
case control studies 
case series 
case reports 
ideas and opinions