








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




Another question about Normal Gaussian Distribution
The purpose of a study by Luglie et al was to investigate the oral status of a group of patients diagnosed with thalassemia major (TM). One of the outcome measures was the decayed, missing, and filled teeth index (DMFT). In a sample of 100 patients, the mean DMFT index value was 18 with a standard error of 1.2.
What percentage of people will be in the interval [6, 42]? a) 50% b) 68.2% c) 81.8% d) 99.7% e) more information is need it 
The above post was thanked by:  
apx85 (05272011), Claus_CU (05282011), mle guy (05282011), Mondoshawan (05282011), pass7 (05272011), singapur_md (05272011) 
#2




SE=SD/square root of n
so SD=SE x square of n =1.2x10(squareroot of 100) SD=12 As mean is 18 ,so 6 will be 1 SD below the mean and 42 will be 2SD above the mean 1SD above and below the mean is equal to 68% and as 42 is 2SD above the mean we will add 13.2% So ,answer will be 81.3% in simple words,34+34+13=81% 
The above post was thanked by:  
bebix (05272011), mle guy (05282011), Mondoshawan (05282011), pass7 (05272011), patelMD (05282011), singapur_md (05272011) 
#3




Quote:

The above post was thanked by:  
bebix (05272011) 
#4




Answer should be c, explained accurately by struggle 81%

#5




YES, the correct answer is indeed C).
point to remember: SD is not the same as SE 
Tags 
BiostatisticsEpidemiology, Step1Questions 
Thread Tools  Search this Thread 
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
USMLE Step 1 Questions Distribution  Percentage of each Subject  StepTaker  USMLE Step 1 Recommended Threads  27  1 Week Ago 02:45 PM 
Normal Gaussian Distribution  rulz  USMLE Step 1 Forum  20  03052012 02:18 PM 
Cushing's syndrome abnormal fat distribution  eesfee  USMLE Step 1 Forum  3  05072011 07:56 PM 
Question Distribution for Step 1?  noone_123i  USMLE Step 1 Forum  1  12162010 01:13 AM 
question distribution in step2 ck..  usmleguy  USMLE Step 2 CK Forum  1  11152010 08:01 AM 
