Statistical significance

Question 1

What does it mean when a result is clinically relevant?

Answer 1

-the reduction has to be large enough to be meaningful for the patient; 5% reduction may be relevant, maybe not, 50% probably is

Question 2

What is statistical significance?

Answer 2

usually set at 5%: 95% chance that the result is a true result and 5% chance on type I error: you assume that there is an effect while there is not

Question 3

sample size and significance

Answer 3

there is an association between the sample size and the chance that the effect is really there (=significance)

• very small sample size –> even a large difference will not become significant (even if its clinically relevant)
• very large sample size –> even small difference will become significant (NOT necessarily clinically relevant)

Question 4

statistical significance depends on…

Answer 4

magnitude/ size of the effect AND number of patients in the RCT