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#1
07-14-2012
 USMLE Forums Addict Steps History: Step 1 Only Posts: 122 Threads: 34 Thanked 24 Times in 15 Posts Reputation: 34
The concept of P Value!

Can someone explain the P value concept in understandable terms?

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#2
07-14-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 433 Threads: 52 Thanked 387 Times in 148 Posts Reputation: 397
well

as far as i know, or at least use for answering questions. if p value less than .05 then the data is statistically significant and u can reject the null hypothesis but if larger then nope.....till now i am solving questions based on this concept and everything is fine al hamdolellah
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 The above post was thanked by: johnvega98 (07-15-2012)
#3
07-15-2012
 USMLE Forums Master Steps History: 1 + CS Posts: 675 Threads: 84 Thanked 424 Times in 206 Posts Reputation: 434

P value:

-It is a pre-set value (a standard you set before starting the study).

-For a study to be significant, the p value has to be less than 0.05 (this means that 95% of the time the study will be right and 5% due to chance).

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So in other words, p value is a way of figuring out the chance of an "error" in your study.
Therefore, p= probability of making a type 1 error.

Last edited by Renaissance; 07-15-2012 at 01:31 AM.
 The above post was thanked by: johnvega98 (07-15-2012)
#4
07-15-2012
 USMLE Forums Master Steps History: 1 + CS Posts: 675 Threads: 84 Thanked 424 Times in 206 Posts Reputation: 434

As a conclusion to all of this:

The association is significant (the study is significant) when:
-Confidence interval lacks the null value of 1.0
-Which means the null hypothesis (Ho) can be rejected (knowing that you could have done a type 1 error)
-p value is less than 0.05

The association is not significant (the study is not significant) when:
-Confidence interval includes the null value of 1.0
-Which means the null hpothesis (Ho) can't be rejected (knowing that you could have done a type 2 error)
-p value is more than 0.05

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I wasn't able to fully understand all these terms until i integrated them like this, hope this helps.
If there's anything incorrect or inaccurate, i would love some feedback.
 The above post was thanked by: johnvega98 (07-15-2012)

 Tags Biostatistics-Epidemiology

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