EBM Flashcards
What is the p value?
A numerical value indicating the probability that this observation has occured due to chance
What are confidence intervals?
A way of indicating a range of values which probably contain the “true” value
What does p stand for?
Probability
What does p = 0.5 indicate?
50-50% chance that it occured by chance
What symbol indicates the null hypothesis?
Ho
What does the null hypothesis state?
That there is no difference between 2 groups
What does p = 0.05 indicate?
95% of time it won’t happen by chance
0.05 = 5% = 1 in 20
5% of time the null hypothesis will be rejected when it is true
What is the difference between a type 1 and a type 2 error?
Type 1 = Rejecting Ho when it is true (seeing a difference when there is none)
Type 2 = Accepting Ho when it is false (failing to see a difference when there is one)
What affects a p value or a 95% confidence interval?
too small group tested - effect too small to be picked up by the sample size (under powered study)
Confunding (hides the effect)
What is statistical power?
Statistical power is the probability of correctly rejecting a false H0, i.e., getting a significant result when there is a real difference in the population.
What affects statistical power?
Effect size
Sample size
moving of critical value
