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. Author manuscript; available in PMC: 2015 Jun 15.
Published in final edited form as: Stat Med. 2014 Jan 20;33(13):2238–2250. doi: 10.1002/sim.6091

Table 1.

Structure of the ZIP Mixture Model*

Component 1 Component k
(k = 2, …, m)
Yij ~ ZIP(λij1, πij) Yij ~ Poisson(λijk)
log(λij1) = β1 + β·xij + uij log(ijk) = βk + β·xij + uij
logit(πij) = ψ·xij + wij
uij ~ N(0, σu2), wij ~ N(0, σu2) uij ~ N(0, σu2)
*

We require β1 < β2 < … < βm to ensure the identifiability of the model.