This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Power of study can be increased by 
Select and explain. 
A. Increasing a error, B. Increasing b error, C. Decreasing a error, D. Decreasing b error
D: Decreasing b error
Answer: D: Decreasing b error 
Explanation: Power of a Test:
– Is probability of rejecting a Null hypothesis when a predetermined clinically significant difference is indeed
present
– Measures the ability to demonstrate an association, when one really exists
– Power of a statistical test: 1 – b ( 1 – probability of Type II error)
– Power of a statistical test is complimentary to b (probability of Type II error)
– Power of a statistical test is a numeric representation of: Sensitivity
– Power of a statistical test can be increased by:
1. Increasing the no. of subjects in a trial (sample size)
2. Reducing b (probability of Type II error)
3. Increasing sensitivity
– Power of a statistical test is also used for calculation of sample size for a study