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  1. USMLE Step 1 Forum
    New chemotherapy regimen is tested on 100 pts with lung cancer. 40 of pts are still alive after 1 yr. Conventional chemotherapy is given to separate group, 500 pts. with lung cancer and 100 are alive after 1 yr.. Calculate NNT. We know NNT = 1/ARR IN DIT THEY SAID THAT FORMULA FOR ARR IS [...
  2. USMLE Step 1 Forum
    1) A city with 1000 citizens has a 10% prevalence of disease x .. Screening shows sensitivity 80% and specificity 70% How many people without disease X will be falsely diagnosed positive by this screening test.. 1) 20 2) 30 3) 270 4) 300 2) A city with 1000 citizens has a 10% prevalence of...
  3. USMLE Step 2 CK Study Partners
    I am planning to give exam in a month..so i need a dedicated sp to discuss important concepts of bio-stats and im quickly an hour everyday..i am from india so will prefer someone from same time zone..my skype id: vivek.dokan
  4. USMLE Step 1 Forum
    Can someone plz explain the difference between effect modification and confounding??
  5. USMLE Step 1 Forum
    For patients with ambulance response intervals of longer than 5 minutes, more patients achieved Return Of Spontaneous Circulation in the CPR first group (58% [37/64]) compared with the standard De-fibrillation first group (38% [21/55]) Whats the OR? I can't figure out the steps to solve this...
  6. USMLE Step 1 Forum
    In my FA I have for some completely forgotten reason scribbled down the words "prevalence odds ratio" and underlined it...and i cant remember wtf its from or what it is....I cant find anything on google, has anyone come across it?! or did i just completely make it up in a moment of study-psychosis?
  7. USMLE Step 2 CK Forum
    1- Confounding bias :(Middle factor that is related to both Exposure and Outcome) Alcohol ( exposure ) Oral cancer ( outcome ) Smoking is a confounding bias here. Because smoking is related to BOTH the exposure and the outcome. People who smoke will more often drink, and people who have...
  8. USMLE Step 1 Forum
    A test yields 80% infected and 10% non-infected.....prevalence is 10%. What is positive predictive value? A. 47% B. 54% C. 75% D. 25%
  9. USMLE Step 1 Forum
    Bias Questions in biostatistics are very confusing. Want to know how to improve my grip on this topic? any advice plz?
  10. USMLE Step 1 Forum
    I know that effect modification is not a bias...however they sound so similar...how do you guys differentiate between the two?
  11. USMLE Step 1 Forum
    Guys right now I am doing Epidemiology from Kaplan and while I was watching kaplan videos and going through notes, I was stuck with these doubts. Please anyone take some time and answer 1) The definition of Sensitivity in Kaplan notes is as follows: "Sensitivity is the proportion of truly...
  12. USMLE Step 1 Forum
    can someone plz tell is FA & uworld enough for these two subjects?? plz rep..thanks in advance..God bless
  13. USMLE Step 1 Forum
    can someone please advice me , how to improve the subject above , i did a stimulated test , and i scored badly for the above two subject , i have used kaplan , dit , but still ..... please advice , thanks .
  14. USMLE Step 1 Forum
    On a gross anatomy quiz, test scores of 10, 10, 10, 70, 40, 20, and 90 are obtained by seven students in a laboratory group. Which of the following correctly describes these quiz scores? (A) Positively skewed (B) A normal distribution (C) Negatively skewed (D) The mode is higher than the mean...
  15. USMLE Step 1 Forum
    A screening test is developed for assessing vulnerability to developing a certain condition. A sample of 10,000 people between the ages of 18 to 24 is recruited from the general population and given the screening test. Of this sample, 200 individuals are identified as likely to develop the...
  16. USMLE Step 1 Forum
    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?
  17. USMLE Step 3 Forum
    what is the most important modified risk factor for CAD: DM HTN Smoking Central obesity Physical inactivity Thanks
  18. USMLE Step 2 CK Forum
    Study is made to analyze the relationship of vitamin B12 and methylmalonyl-COA level. Researchers show that there is an inverse relationship, the correlation coefficient is -0.7 (p<0.05). How much variability in plasma methylmalonyl-COA is explained by B12 intake? A) >0.95 B) 0.70 C) <0.05 D)...
  19. USMLE Step 1 Forum
    So I've done every single NBME from the offline and online forms. There are questions in the newer forms where it tests material that isn't in Kaplan or FA. Anybody know where I can go to fill these gaps in? For instance, they talk about "internal validity". Don't recall seeing this anywhere...
  20. USMLE Step 2 CK Forum
    Guys..where to do the biostats for CK from? hardly anytime left :(
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