RCT's Flashcards
What do RCT’s investigate?
The effect of any sort of intervention.
What standard of investigation are RCT’s often regarded as?
The ‘Gold Standard’.
What three questions are often asked with RCT’s?
Superiority, non inferiority, safety effect.
What is the purpose of randomisation?
To balance known and unknown covariates between treatment and control groups.
How can you remove allocation bias?
Through randomisation.
What value of n is needed for simple randomisation to be a viable form of randomisation?
200+
Why is varying block sizes good in blocked randomisation?
Stops practitioner bias.
Block sizes are always random in blocked randomisation. True or false?
False. They can be preset.
What is the advantage of using larger block sizes in blocked randomisation?
Order of events is less predictable.
When would the latin square technique be used with block randomisation?
When there are repeated measures of a treatment for a particular individual.
Do you stratify before or after blocking?
Before.
Stratification variables should be of _____ significance.
Prognositic.
Name four variables you can stratify by.
Gender, age, disease status, assessment centre.
What is the goal of minimisation?
To maintain balance of stratification variables during allocation.
When is minimisation and effective randomisation technique?
Small studies with multiples stratification factors.
When interventions vary between regions (eg vaccine interventions, verbal GP interventions) what sort of randomisation should be used?
Cluster randomisation.
What is an advantage of cluster randomisation?
It reduces risk of the intervention contaminating the control group.
Why is blinding necessary?
As randomisation alone does not prevent differential treatment later on.
Who is blinded in a triple blinded trial?
Participants, investigators, assessors.
Why are sham procedures not used anymore?
They are unethical.
Do parallel randomised trials require the same amount of people in each arm?
No.
What sort of comparisons are made in a parallel studies?
Between person comparisons.
When are crossover studies used?
When you need more statistical power (when the studies are small).
What type of conditions are crossover studies good for?
Chronic.
