ManuNastai wrote:
it is e, but is 180*1500/120*1000
I am with you
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| pearljam59
Forum Guru
Topics: 120
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I believe it is C.
I do not know what First Aid is doing with there definition of relative risk and complex multiplication/division.
Relative risk is merely a RATIO.
Breast cancer in childless woman / Beast cancer in woman with children
180/120
1.5
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| guest007
Forum Senior
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i agree with pearljam59....word to word....
kaplan and brs...both have mentioned the same stuff in detail......first aid may be wrong here...beware...they have written something about a test......in the table format....i think they have got it wrong ...they are also students like us 
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| robin082006
Forum Hero
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E but different calculation
Relative risk= (a/a+b)/(c/c+d)= (180/1000)/(120/1500)= 180*1500/(120*1000)=3*15/(2*10)=2.25
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| guest007
Forum Senior
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hi robin082006,
whats your reference book for the above calculations.....and formula.
my reference for going with pearljam59 was page no.110 HIGH YIELD behaviorialscience.second edition.by fadem.
ur formula does make a sense infact but let me know the reference.
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| mjl1717
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doing it roughly in my head I got answer -e-comments (although there should not be much revelation on a q like this.) [one of those plug in the #s]
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| robin082006
Forum Hero
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Hi guest007,
It is in
Kaplan and FA.
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| guest007
Forum Senior
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hi.....even after going back to kaplan and HY i analysed tht the answer is simple.....breast ca in childless woman and with child....is 180 /120....1.5.
forget about how many are not having breast ca.!as this is only a relative risk (ratio)....
but it seems many people are just following E as the answer........anyways i will go with c again.hoping tht this question does not appear in my exam.
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| netlover
Forum Junior
Topics: 3
Posts: 54
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Hi, guest007, look at the following link, you will know the answer should be E. From kaplan notes, there is an example using just two numbers like you said. However that is because in that case, a+b = c + d (both are 1000). So I guess that the author just skip the two 1000s.
http://www.musc.edu/dc/icrebm/oddsratio.html
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| netlover
Forum Junior
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I forgot to give you another link
http://www.mindspring.com/~hlthdata/ex-rr1.html
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| robin082006
Forum Hero
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It's a mistake guest007 if you think your calculation is right because it's only correct if two samples are equal as netlover mentioned.
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| guest007
Forum Senior
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thanks guys ......big mistake from kaplan actually may be they have rectified ion new addition....thanks alot guys.
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| iirrum
Forum Junior
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can any one explain how value of a in the formula is 180.
i think women ith children having breast ca 120 should be a in the formula.
then ans should be option A
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| doctorsaib
Forum Newbie
Topics: 2
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The answer is E (2.25).
Risk ratio is defined as risk in EXPOSED/Risk in UNEXPOSED. The "exposure" here is having a child. The "disease" is breast CA.
However, the question asks for RR for a CHILDLESS woman compared to a woman with a child. So the set-up is (c/c+d) / ( a/a+b). The RR for a CHILDLESS woman is therefore 0.18 / 0.08, which equals 2.25.
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| study_ing
Forum Fanatic
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try not to go for numbers.
risk in childless women= probability of childless woman having cancer
=childless women with cancer/total CHILDLESS women (180/1000)
risk of Br ca in women with children=120/1500
therefore relative risk= ratio of the two risks
180 into 1500
1000 into 120
the formula shud be used only to help u. if it causes confusion think it out
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| study_ing
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enthu u have calculated the odds ratio....we were asked about relative risk
pearljam 59 NEVER USE just numbers.
risk in itself is a probability (a ratio)
relative risk is a ratio of 2 risks
sorry to sound harsh but this is something the board loves to confuse students with
...
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| asankineni
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E- Beyond doubt. Since relative risk is a ratio of incidences
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| zubr
Forum Junior
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Posts: 61
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Agree with E
Relative risk= I1/I2 = (a/(a+b)/(c/(c+d)= (180/1000)/(120/1500)= 2.25=E
You can devide 180/120 only you have SAME population (sample) at risk.
In this case 1000 does not equal to 1500.
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| zubr
Forum Junior
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Posts: 61
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Q: Based on these data, what is relative risk (risk ratio) for development of breast cancer in childless women compared with women who have children?
RR= R1 childless/R2 have children = E
If they asked: Based on these data, what is relative risk (risk ratio) for development of breast cancer in women who have children compared with childless women ?
RR=R2 have children/R1 childless = 0.44
RR<1 tells about a protective factor, not a risk factor
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| Cedrick
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Thank you for the hard work
E
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