# Re: st: Use of the term 'relative risk ratio'

 From Michael Ingre To statalist@hsphsun2.harvard.edu Subject Re: st: Use of the term 'relative risk ratio' Date Thu, 21 Apr 2005 19:09:13 +0200

Many thanks to Roberto G. Gutierrez, StataCorp, for your very clear and pedagogical description of the RRR concept and how it is used by Stata. Maybe some of the confusion about RRR is related to pronunciation (or me not being a native in English)?

(1) relative-risk ratio - a ratio of two relative-risks
(2) relative-risk-ratio - a ratio of two relative-risks
(3) relative risk-ratio - a risk-ratio that the describe the relative of two (absolute) risks

I'm currently writing a paper using a special case of number 3 above that I don't know how to present (used to call it RRR). The normal use is just risk ratio (RR) comparing the risk of having a disease compared to not have it. However, suppose you estimate a -logit- and want to describe the ratio between the risk given one level of the exposure to the risk given another level. These ratios will not behave like normal RRs across the levels of the exposure because of the S-shaped (logistic) probability function. What would you call these ratios: RRs or RRRs ...?

p1 = P(Y=1 | x+1) q1 = p(Y=0 | x)
p2 = P(Y=1 | x=2)
p10 = P(Y=1 | x=10)

p1
RR = ----
q1

p10
?? = ----
p2

Any suggestions?

Thanks

Michael

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