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 3strange points in biostatistics  



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Author4 Posts
  #1

I am sorry but i am writing here because no epidemiology category

q1
in is pg of boistatistics chapter in Kaplan psychiatric note book
if the event r nonindependent.....e,g if one has a box with 5 white & 5 blacks balls in it,the chance of picking two blacks balls is (5/10)x(4/9)=0.5x0.44=0.22(or 22%)
can u plz explain from where that equation comes from !!!!!!!!!!!!!!!!!


q2 in Kaplan epidemiology video when he explain the equation if fat=30% &DN=10%
calculate the chance of meet fat or DM or both he said (A+B)-(AxB)
BUT if ask chance of meet fat or DM not both he said (A+B)-2AB BUT i think the equation should be (A+B)-2(A/B) correct me if I am wrong

q3 can u explain the answer of the last q (q6 ) in Kaplan note 2008-2009
which is article with tabular data of relative risk of DM the answer was c
which is :Level 3 and 4 are significantly different from baseline and risk elevation>
why not a,b,d,e
again I am sorry but iam writing here because no epidemiology category








  #2

is this for step 2 ?


  #3

yes, step 2
from kaplan note of psychatric & epidemiology2008-2009
in chapter 2 biostatistic page:141
combine propapility
in is pg of boistatistics chapter in Kaplan psychiatric note book
if the event r nonindependent.....e,g if one has a box with 5 white & 5 blacks balls in it,the chance of picking two blacks balls is (5/10)x(4/9)=0.5x0.44=0.22(or 22%)
can u plz explain from where that equation comes from !!!!!!!!!!!!!!!!!
------------------------------------------------------------------------------------
in biostatistic page:155 the last q
can u explain the answer of the last q (q6 ) in Kaplan note 2008-2009
which is article with tabular data of relative risk of DM the answer was c
which is :Level 3 and 4 are significantly different from baseline and risk elevation>
why not a,b,d,e
again I am sorry but iam writing here because no epidemiology category


nod the whole note is easy except those


  #4

omg i hate math, i thought i was done with this stuff grin .. anyways have no idea and dnt have the kaplan books but

what i remember from step 1 is that for non-independent ( dependent ) event u assume that one has already occured. so if there were 10 balls 5 white and 5 black the chance of u picked black is 5/10 but if u picked one already and one to pick again so 4/9 and the chance of white still is 5/10 since u can still pick those. they basically depend on each other thats the main thing.

the other thing i just look at my old f.a book for step 1 and i have a+b - 2(axb) ..

i dnt think it can be division because when u divide fractions they actually increase like .30/.10 = 3 vs .30 x .10 = .03 i mean the chance of finding someone with both and not both should be harder than finding with one thing. i dnt know if that makes sense. but anyways good luck man





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