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Analysis of Cancer Risks in Populations Near Nuclear Facilities Phase 1 (2012) / Chapter Skim
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Appendix J: Modeling Incidence and Mortality Data in an Ecologic Study
Pages 389-394

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From page 389...
... (1) Here mi is the expected value of Ni (i.e., the number of cancer incident cases or deaths in a particular geographic unit expected from broad population rates, typically cross-classified by other variables such as age, gender, and race/ethnicity with i as the identifying index)
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From page 390...
... , multiplied by person-years at risk, and the ERR parameter b is the excess relative risk associated with dose or dose surrogate Di. Much more complex models can be considered and software for generalized Poisson regression is available (Epicure, Hirosoft Software, Seattle, Washington)
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From page 391...
... J.2 PERSON-YEAR CALCULATIONS Another key issue in Poisson modeling is to adequately approximate person-years of exposure to some hazard, pyi, as well as counting the number of events Ni. For each cell in the tabulation of events cross-classified by geographical unit, race, age, and calendar time, census data are required in order to determine the population size for each table entry, i.e., the whole population must be classified according to these same variables.
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From page 392...
... can be used to compute variances of the parameter estimates that adequately reflect the variability of the counts. The overall approach described above relates observed disease rates to distance or other dose surrogates in a systemic way, i.e., addressing the question of whether or not disease risk appears to be associated with proximity to a nuclear facility, or to other dose surrogates, averaging over all the facilities.
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From page 393...
... . Poisson overdispersion estimates based on the method of asymmetric maxi mum likelihood.
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Key Terms

  • dose surrogates
  • geographical unit
  • poisson model
  • calendar time
  • generalized linear

  • poisson distribution
  • background rate
  • disease risk
  • disease rates
  • using poisson

  • random variable
  • observed counts
  • census tract
  • cumulative dose
  • regression models

  • relative risk
  • excess relative
  • dose surrogate
  • err parameter
  • model incorporates

  • simpler dose
  • particular plant
  • risk associated
  • overdispersion term
  • adequately approximate

  • random fluctuation
  • err model
  • covariate value
  • socioeconomic variables
  • highly mobile


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