Significant P Value but not much difference! - USMLE Forums
 USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
 Home USMLE Articles USMLE News USMLE Polls USMLE Books USMLE Apps
 USMLE Forums Significant P Value but not much difference!
 Register FAQs Members List Search Today's Posts Mark Forums Read

 USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam

#1
08-26-2013
 USMLE Forums Guru Steps History: Not yet Posts: 339 Threads: 94 Thanked 330 Times in 150 Posts Reputation: 290
Significant P Value but not much difference!

Smokers among males = 35% in a population.
Smokers among female = 34.1%.
Chi square was done between the two groups and P<0.05

Is that possible? can be the difference between them significant although the percentage between the two populations is close?

#2
08-26-2013
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 3,263 Threads: 147 Thanked 4,993 Times in 1,563 Posts Reputation: 5089

Yes. That's possible.

The P Value is not correlated to the amount of difference or resemblance between two datasets. It's correlated to "How true is the observation".

So in your example above, you can be sure that the difference is small between the two groups.

-
 The above post was thanked by: earthpole (08-26-2013), Insomniac (08-26-2013), Mo-tongji (08-27-2013)
#3
08-26-2013
 USMLE Forums Addict Steps History: 1+CK+CS Posts: 161 Threads: 10 Thanked 76 Times in 55 Posts Reputation: 89

If you want to measure the clinical difference between two groups you can use for example: number needed to treat.
If this number if too high it would mean that if although there is significant difference between the two groups the clinical meaning of this difference is not very important.
 The above post was thanked by: earthpole (08-26-2013), Insomniac (08-26-2013)
#4
08-26-2013
 USMLE Forums Guru Steps History: Not yet Posts: 339 Threads: 94 Thanked 330 Times in 150 Posts Reputation: 290

Thank you so much for the explanation!

 Tags Biostatistics-Epidemiology

Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
User Name:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
 AMG IMG ---
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

 Not yet Step 1 Only CK Only CS Only 1 + CK 1 + CS 1+CK+CS CK+CS 1+CK+CS+3 ---
Favorite USMLE Books
 What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
 Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.