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From |
"Carlo Lazzaro" <carlo.lazzaro@tin.it> |

To |
<statalist@hsphsun2.harvard.edu> |

Subject |
st: R: probability question |

Date |
Wed, 11 Jun 2008 10:28:51 +0200 |

-----Original message----- On 2008 June 10 moleps islon wrote: Dear statalisters, can someone help me out with this basic question? I need to calculate the probability of the following event: That at least one patient out of 99 suffers from kidneycancer (incidence 15/100000 pr year) over a time period of 15 years. Dear Moleps, searching the literature (Briggs A, Sculpher M, Claxton K. Decision Modelling for Health Economic Evaluation. Oxford: Oxford University Press, 2006:51) I have found out a formula for converting rate into probabilities: p=1-exp(-rt) where: p=probability; r= instantaneous rate, provided that it is constant over the period of interest (t) Hence, your 15-year probability would be: Display 1-exp(-15/100000*15) .00224747 and your 1-year probability would be: display 1-exp(-15/100000*1) .00014999 // that is, around 15 new cases per year. Eventually, I have tried to sketch a temptative answer to your question, referring to the 1-year probability that at least one patient convert to kidney cancer: Display 1/100000+1/99999+1/99998+1/99997+1/99996+1/99995+1/99994+1/99993+1/99992+1/9 9991+1/99990+1/99989+1/99988+1/99987+1/99986 .00015001 I do hope that my last try will not mislead you. Probably, Stata gurus on the list can support you with a better solution. HTH and Kind Regards, Carlo * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/support/faqs/res/findit.html * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st: probability question***From:*"moleps islon" <moleps2@gmail.com>

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