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#1
12-11-2010
 USMLE Forums Addict Steps History: 1 + CS Posts: 103 Threads: 29 Thanked 18 Times in 13 Posts Reputation: 28
How to calculate the power of a study ?

hey ppl plzzz help me out with this ......how to determine the power of a study ? ....how to calculate it?....i cant figure it out :O pllzzzzz helpppp!!!

#2
12-11-2010
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 742 Threads: 137 Thanked 2,428 Times in 441 Posts Reputation: 2531
1 - type II error

The power of a statistical test is the probability that the test will reject a false null hypothesis (i.e. that it will not make a Type II error). As power increases, the chances of a Type II error decrease. The probability of a Type II error is referred to as the false negative rate (β). Therefore power is equal to 1 − β, which is equal to sensitivity.
 The above post was thanked by: Carolina_USMLE (12-18-2014)
#3
12-11-2010
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 742 Threads: 137 Thanked 2,428 Times in 441 Posts Reputation: 2531
Don't confuse it with accuracy

The accuracy of the study is different.

It's calculated by the following formula:

Accuracy = TP + TN / TP + FP + TN + FN
#4
12-11-2010
 USMLE Forums Addict Steps History: 1 + CS Posts: 103 Threads: 29 Thanked 18 Times in 13 Posts Reputation: 28

thxxxx sooo much for ur reply rasheed .....n plzzz can u explain it with an example
#5
08-25-2011
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,357 Threads: 194 Thanked 3,259 Times in 881 Posts Reputation: 3269

Quote:
 Originally Posted by rasheed The power of a statistical test is the probability that the test will reject a false null hypothesis (i.e. that it will not make a Type II error). As power increases, the chances of a Type II error decrease. The probability of a Type II error is referred to as the false negative rate (β). Therefore power is equal to 1 − β, which is equal to sensitivity.
Therefore power is equal to 1 − β, which is equal to sensitivity??

 Tags Biostatistics-Epidemiology

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