This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Statistical Errors, p-value, Subject name: Social & Preventive Medicine
Statistical Power of a trial is equal to: 
Select and explain. 
A. 1 + a, B. 1 - b, C. a + b, D. a / b
B: 1 - b
Answer: B: 1 - b 
Explanation: Statistical power of a test Power of a statistical test = 1 - probability of type II error = 1 -b Is probability of rejecting a Null hypothesis when a predetermined clinically significant difference is a indeed present Power can be increased by increasing the no. of subjects in a trial