Biostatistics Flashcards
standard deviation normal distribution a 68%
SD a 1 from the mean
standard deviation normal distribution a 95%
SD a 2 from mean
standard deviation normal distribution a 99,7%
SD a 3 from the mean
example mean a 230 mg/dl pour le cholesterol and SD a 10,what’s the value for cholesterol if observations are 95%
210-250
disease with increasing prevalence and stable incidence what happened(2)
any rx which prolongs life
good quality of care
Quid of PPV(2)
positive predictive value
pobability of having the disease if the result test is positive
quid of negative predictive value
probability of having the disease if the test is negative
quid of null hypothesis
no relationship between exposure and outcome
example of null hypothesis
CRP high and colon cancer ,no relationship
what to consider when evaluating the effectiveness of new trial drug
the natural history of the disease
example drug effectiveness and drug trial(2)
effectiveness of antiviral drug and flu
no exact conclusion can be drawn becausecommon cold is a self limited disease
in hazard ration interpretation what are the 2 key factors to consider(2)
control arm
rx arm
quid of hazard ratio <1
the event will occur in the control arm
quid of hazard ratio > 1
the event will occur in the rx arm
practice of hazard ratio
the chance for an event to occur during taking a drug for instance
interpretation of hazard ration close to one
no difference for an event to occur in the 2 groups rx arm and control arm
what information is critical to successfull randomization
baseline characteristics
what an ideal randomisation
process to minimize selection biais and achieves possibility of cofounding variables
a study is done using placebo and Rx,the assignment of the rx in teh two arm is done randomly using numbers generated by computer what randomization helps to do in ths case?
to eliminate confounder
what methods are used to eliminate cofounder during analytic stage of study
stratified analysis
modeling
what methods are used to eliminate cofounder during adesign stage of study(3)
matching
restriction
randomization
clue for randomization(2)
Rx group
Placebo group
when using randomization
during clinical trials
quid of restriction
when you limit your study to one group for example one sexe is considered