Stats Study designs for new drugs

Question 1

If a drug is therefore to be compared to an existing treatment a statistician will need to decide whether the trial is intended to show

Answer 1

superiority, equivalence or non-inferiority:

Question 2

Superiority

Answer 2

whilst this may seem the natural aim of a trial one problem is the large sample size needed to show a significant benefit over an existing treatment

Question 3

Equivalence

Answer 3

an equivalence margin is defined (-delta to +delta) on a specified outcome. If the confidence interval of the difference between the two drugs lies within the equivalence margin then the drugs may be assumed to have a similar effect

Question 4

Non inferiority

Answer 4

similar to equivalence trials, but only the lower confidence interval needs to lie within the equivalence margin (i.e. -delta). Small sample sizes are needed for these trials. Once a drug has been shown to be non-inferior large studies may be performed to show superiority