Different types of study design Flashcards
How is results being due to chance minimised?
large sample size and statistical analysis
p value of < 0.05 means
less than 5% chance the difference between the two results is due to chance
confounding factors
factors that affect the interpretation of outcomes
P
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C
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Who are the patients and what is the problem
Intervention / exposure
control / comparison
outcome
Types of observed analytical studies?
cohort
case-control
cross section
RCT pros
Allows for robust statistical analysis
Blinded
Reduced bias due to randomisation (confounders less likely to impact results)
RCT cons
Ethical concerns
Expensive
Large resources needed to carry out
Volunteer bias
What is an RCT crossover trial
Patients act as their own control
Try one treatment for a set period then another. compare outcomes
When can an RCT crossover trial not be used?
treatment with permanent effect
Cohort study
Two groups identified, those who have or have not got the disease / had intervention / had an exposure and followed up to find out a certain outcome
Cohort study pros
investigate an exposure
can match participants
eligibility criteria can be set
standardised outcome
assessment
less ethical issues
still prospective study
may lose to follow up
Cohort study cons
Exposure may be linked to a hidden confounder
no blinding
no randomisation
difficult to identify controls
Case control study pros
quick and cheap
useful in rare disorders
case control study cons
retrospective
documentation may not be reliable - recall bias
confounders
what is a case control study
retrospective analysis of two groups (e.g. one with disease and one without) and looking to see if there is a correlation with a certain exposure
