r753_2000
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This question is EXACTLY the same question I had on my exam... only the variables are different. Does anyone know how to get the answeR? Biostatistics is my worst subject.
A new treatment for elevated cholesterol is piloted on a sample of 10 men, ages 45-59 wtih total serum choleterol in teh range of 260-299 mg/dl at entry. Following 3 months on the medication, the mean cholesterol fr the treatment grop was 250 mg/dl with a standard deviation of 20 mg/dl. What is the 95% confience interal on the mean for this study?
a) 210-290 mg/dl
b) 230-270 mg/dl
c) 246-254 mg/dl
d) 248-252 mg/dl
e) 249-251 mg/dl
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| ELM
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C,... 95% CI=1.96 and includes 2 SD -----> 1.96x2=almost 4---> so the mean is 146-254.
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| r753_2000
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Thanks elm. appreciate that!
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| r753_2000
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How about this one?
The wechsler adult intelligence scale - revised (WAIS-R) is a standardized IQ tet with a mean of 100 an a stndard deviation of 15. A person with an IQ of 115 is what percentile of IQ?
a) 50th
b) 68th
c) 84th
d) 95th
e) 99th
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| ELM
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84th....1st SD is 84, 2nd SD is 97.5.....goes on.
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| r753_2000
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how did you get that 84 is the first standard deviation? did you subtract 15 from 100?
if you subtracted it from 100.. then how you get 2nd sd of 97?
sorry for being a butthead. i hate biostatistics
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| mash
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hey, regarding ur 1st q
95%CI=mean+/-z(sd/sq root of n)
=250+/-2(20/sq root of 10)= 250+/-12.5= 237.5--262.5
if n =100 then it wud be 246-254
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| SA
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but n= is 10 so what is the right option in this q 1 as I also calculated as way as you did but it is none of the option?
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| SA
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"ELM" wrote:
84th....1st SD is 84, 2nd SD is 97.5.....goes on.
Regarding this question what will be the percentile of IQ if his IQ is 110 (what I get from your ansewer the it should be 84 sd it is also within first standard deviation :?: )
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| ELM
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Mash, look it up on Kaplan's 2004 Phychiatry note p=154, q#4 says answer is -----> 246-254. :!:
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| SA
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"r753_2000" wrote:
This question is EXACTLY the same question I had on my exam... only the variables are different. Does anyone know how to get the answeR? Biostatistics is my worst subject.
A new treatment for elevated cholesterol is piloted on a sample of 10 men, ages 45-59 wtih total serum choleterol in teh range of 260-299 mg/dl at entry. Following 3 months on the medication, the mean cholesterol fr the treatment grop was 250 mg/dl with a standard deviation of 20 mg/dl. What is the 95% confience interal on the mean for this study?
a) 210-290 mg/dl
b) 230-270 mg/dl
c) 246-254 mg/dl
d) 248-252 mg/dl
e) 249-251 mg/dl
Let me clear the confusion both of you are right as when I read the question I did the calculation as mash did and my answer was same as mash's was but it was not in the option so I did not post anything but confused :? about ELM explanation as this not the formula when N is less then 100 ok but now after reading ELM last post I got every thing clear when he read the question he know it from Kaplan and know the right answer and explanation but there a difference in this question (I think by mistake) that r753_2000 Wright in 10 men rather then 100 ok I hope every one is clear now so the answer for this on will be with 10 men 237.5--262.5 but if 100 men included in study then ELM is right :o
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| SA
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"r753_2000" wrote:
How about this one?
The wechsler adult intelligence scale - revised (WAIS-R) is a standardized IQ tet with a mean of 100 an a stndard deviation of 15. A person with an IQ of 115 is what percentile of IQ?
a) 50th
b) 68th
c) 84th
d) 95th
e) 99th
but still not clear about this q :?
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| r753_2000
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yes SA, for the first question, there are a sample of a 100 men and not 10. ok...
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| ELM
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:lol: :lol: :lol: what a mess????!!!!
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| ELM
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Here we go to those who are little confused with percentiles!
+1st SD=84th, where as -1st SD is 16th
+2nd SD=97.5th, where as -2nd SD=2.5th
+3rd SD=99.9, -3rd=0.11
Have to memorize these numbers, no other way around.
Hope it's clear now for you.
To SA if IQ=110 i think it will be still 1st SD so 84th.
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| r753_2000
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isn't 1st SD 68% 2nd SD 95.5% and then 3rd SD 99.7%
from kaplan epidemilogy and ethics page 144
again, my apologies for confusing everyone with the first question
hehe
but how about this one?
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| SA
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Thanks ELM I got it know so no other way just to learn it by heart and I hate it :cry:
I am trying to make some question of this type (epi and biostat) and will post soon!
But please tell me is it worth while to spend some time on that as for as real exam is concern?
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| ELM
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r753,
That's the persent you are talking about, not percentile!!! They are diffirent stuff. You need to memorise the numbers that you mentioned and the numbers that i gave you too. One is persent, the other is persentile. We need to know both of them!
To SA I don't know how much we should pay atention to Biostatistics, but i assume we need to know at least these numbers and 2x2 table by heart. 8)
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| sar
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Elm,
for biostats, Crush + uw questions or any other questions + FA (of step one biostats part) would be enuf. Read all explnations of all questions.
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| SA
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"sar" wrote:
Elm,
for biostats, Crush + uw questions or any other questions + FA (of step one biostats part) would be enuf. Read all explnations of all questions.
I had one Crush by Brochert! is it the same Crush you are talking about?
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| sar
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Yes, i am talking about "Crush the Board" by Adam Brochert.
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| SA
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I had crush the step 2 by Brochert I think is the same book?
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| ELM
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The same thing, SA :lol: .
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| SA
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Thanks ELM
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| noelle
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TO r753_2000 DO U REMEMBER MORE QS FROM THE EXAM :?: .. IF YEAH CUD U POST THEM ON SOMEWHERE . IT WUD B HELPFUL 
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