Biostat - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
USMLE Articles
Go Back   USMLE Forums > USMLE Step 1 Forum

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
Old 11-03-2012
USMLE Forums Addict
Steps History: 1+CK+CS
Posts: 106
Threads: 35
Thanked 17 Times in 10 Posts
Reputation: 27
Default Biostat

Serum LDL conc are measured in blood sample collected from 100 healthy volunteers. The data follow normal distribution. The mean and standard deviation for this group is 130 mg/dl and 20mg/dl. Standard error of mean is 5.0. 95 % confidence interval about mean is 120 - 140 mg/dl. If blood samples are collected from 25 volunteers instead of 100, which of the following best expressed the expected impact on standard error and 95% confidence interval about the mean ?
Standard error Width of 95% CI
A. de de
B. de in
C de no change
D in de
E in in
F in no change
G no change de
H no change in
I no change no change
Reply With Quote Quick reply to this message

Old 11-03-2012
venky2600's Avatar
USMLE Forums Master
Steps History: 1+CK+CS+3
Posts: 1,186
Threads: 119
Thanked 814 Times in 434 Posts
Reputation: 824
Send a message via Yahoo to venky2600

i think it's E..........increase increase

if sample size decrease------standard error increase which eventually increase 95% CI .

Reply With Quote Quick reply to this message
Old 11-03-2012
USMLE Forums Master
Steps History: 1+CK+CS
Posts: 1,040
Threads: 189
Thanked 557 Times in 318 Posts
Reputation: 567
Default my answer :)

E in in
Reply With Quote Quick reply to this message


Quick Reply

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
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.
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.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Where you live. Leave blank if you don't want to tell.


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

Similar Threads
Thread Thread Starter Forum Replies Last Post
Biostat for step 2 Ayman Qasrawi USMLE Step 2 CK Forum 0 08-18-2012 09:14 PM
UW biostat qbank!!! hypermedic USMLE Step 1 Forum 2 07-04-2012 08:28 PM
Biostat - p value Rookie USMLE Step 1 Forum 6 06-20-2012 04:03 AM
Biostat dr.dhruvdesai USMLE Step 2 CK Forum 1 03-03-2012 04:31 PM
How to learn biostat??? bronchiole USMLE Step 1 Forum 7 04-01-2011 07:57 AM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)