Comparing two patient groups - USMLE Forums
 USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
 Home USMLE Articles USMLE News USMLE Polls USMLE Books USMLE Apps
 USMLE Forums Comparing two patient groups
 User Name Remember Me? Password
 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

 Thread Tools Search this Thread Display Modes
#1
10-11-2012
 USMLE Forums Scout Steps History: Not yet Posts: 14 Threads: 7 Thanked 2 Times in 2 Posts Reputation: 12
Comparing two patient groups

I can't get my head around the following question. Could someone answer and explain plz. Here it goes....

Two drugs, X and Y are being evaluated for treatment of CHF. Pts receiving drug X have cardiac index of 2.5 L/m2 (square) with 95% CI 1.5 to 3.5. Pts on drug Y have cardiac index of 1.7 L/m2 with 95% 0.7 to 2.7. A test of the significance of difference shows a p-value of 0.1. Which of the following is the likelihood that the difference in mean cardiac index of patients receiving drug X and drug Y is due to chance?

A) 0%
B) 2.5%
C) 5%
D) 7.5%
E) 10%
F) 66.7%
G) 95%

TBH, I don't even know WTH is it asking.....

#2
10-11-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 331 Threads: 39 Thanked 308 Times in 117 Posts Reputation: 318

E) 10 %, because p=0.1, which means there is a 10% probability that the difference between the 2 drugs is due to chance.
 The above post was thanked by: Drmedic (10-11-2012)
#3
10-11-2012
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,186 Threads: 119 Thanked 822 Times in 434 Posts Reputation: 832

Quote:
 Originally Posted by Teona E) 10 %, because p=0.1, which means there is a 10% probability that the difference between the 2 drugs is due to chance.
thanks for explanation....but i got a doubt..
here the 2 drugs 95%CI are overlapping---means there is no difference exist right? from kaplan videos.......
correct me ,i always get confused with these
thanks

#4
10-11-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 331 Threads: 39 Thanked 308 Times in 117 Posts Reputation: 318

Quote:
 Originally Posted by venky2600 thanks for explanation....but i got a doubt.. here the 2 drugs 95%CI are overlapping---means there is no difference exist right? from kaplan videos....... correct me ,i always get confused with these thanks
Yes, if the 2 confidence intervals overlap that means the groups are not significantly different in their outcomes. And p value states the same thing p>0.05, which means there is no difference.
 The above post was thanked by: venky2600 (10-11-2012)
#5
10-11-2012
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,186 Threads: 119 Thanked 822 Times in 434 Posts Reputation: 832

Quote:
 Originally Posted by Teona Yes, if the 2 confidence intervals overlap that means the groups are not significantly different in their outcomes. And p value states the same thing p>0.05, which means there is no difference.
thanks,

i thought 0% as answer..as no difference exist...
#6
10-11-2012
 USMLE Forums Guru Steps History: 1+CK+CS Posts: 331 Threads: 39 Thanked 308 Times in 117 Posts Reputation: 318

Quote:
 Originally Posted by venky2600 thanks, i thought 0% as answer..as no difference exist...
In my opinion, you could choose A) 0% when p value is< 0.05.

p<0.05 means that there is a statistical significance between the 2 drugs, which means that there is almost 0% chances that the statistical difference between the 2 is by chance.
 The above post was thanked by: venky2600 (10-11-2012)

 Tags Biostatistics-Epidemiology, Step-1-Questions

Message:
Options

## Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
User Name:
 Please enter a valid email address for yourself. Email Address:
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

 User Name Remember Me? Password
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.

 Thread Tools Search this Thread Search this Thread: Advanced Search Display Modes Linear Mode

 Similar Threads Thread Thread Starter Forum Replies Last Post Casandra USMLE Step 1 Forum 7 08-23-2012 08:40 AM DocSikorski USMLE Step 1 Forum 12 05-04-2012 12:50 PM deji USMLE Step 1 Forum 0 06-19-2011 06:00 PM harlesmd USMLE Step 1 Forum 15 04-22-2011 06:46 AM priya1 USMLE Step 1 Forum 4 01-03-2011 10:21 AM

 Home - Contact Us - Forum Rules - Advertise - Mobile Site - Archive - Privacy Statement - Top