randomised control trials
- Created by: courteny
- Created on: 11-02-19 15:06
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- randomised controlled trials
- seeks to measure and compare outcomes of 2 or more interventions involves hyopthesis testing and or/ estimation of treatment effects
- pps are ideally selected and allocated at random to recieve one of interventions
- random allocation tries to ensure that both groups have similar characteristics at the outset of the study
- one condition is regarded as the standard comparison or control. in clinical trials this could be standard care or an attention control
- blinding single blind - researcher is unaware double blinded - pps and researcher is unaware
- hypothesis a statement of the relationship that we expect to observe between 2 or more variables
- null hypothesis the asumption that there is no relationship between the independent variable and the dependent so RCT set out to disporve the null hypothesis
- power probability of rejecting the null hypothesis when the alternate hypothesis is true
- the minimum accepted power level is considered to be 80% which means that there is an 8 in 10 chance of detecting a difference of the specified effect size.
- inadequate sample size is one of the principal causes of type 11 error
- type 1 error - null hypothesis rejected type 2 error - null hypothesis not rejcted
- can be difficult to recuit people into a trial when they dont knw what treatment they will get
- strategies need to be inplace in case the new treatment is significanlty better than expected
- ethical issues can be copmlex, particularly if wishing to compare a treatment againest a placebo
- practically, it is not always possible to make conditions ideintical expect treatment.
- hawthorne effect - alteration of behaviour due to awareness.
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