All are true about P-value except: (A) Is the probability of committing Type-I error, (B) When P-value is less than a, the result is statistically significant, (C) Is the chance that the presence of difference is concluded when actually there is none, (D) Is equal to 1-b
Answer is D. • ‘Type I error is usually fixed in advance’ by the choice of level of significance employed in the test
• Type I error is more serious than Type II error
• Power of a test: 1 – b
– Is probability of rejecting a Null hypothesis when a predetermined clinically significant difference is indeed present
– Power can be increased by increasing the no. of subjects in a trial