MBC - Workshop on Model Based Clustering
Hospital differences in caesarean
deliveries in Sardinia:
case-mix or something more?
A Bayesian non-parametric approach
Massimo Cannas, Claudio Conversano, Francesco Mola
Department of Business and Economic Sciences
University of Cagliari
Emiliano Sironi
Department of Statistical Sciences
Catholic University of the Sacred Heart
MBC2
Workshop on Model-Based Clustering and Classification
Catania, 5-7 settembre 2016
MBC - Workshop on Model Based Clustering
Some facts about caesaren section rates
• Recommended rate (World Health Organization)
• Observed rate in Italy
10%
36%
• Significant inter-hospital variability
Two related questions:
1. Can variability be explained by mother-level characteristics? ("case-mix" argument)
2. Are hospital-level variables an important determinant of caesarean section rate?
MBC - Workshop on Model Based Clustering
A Bayesian approach: likelihood…
Yi | pi ~ Bern(pi )
" pi % L
log $
' = ∑ βl xil + h j(i)
# 1− pi & l=1
i = 1,..., n of mothers
j = 1,..., n of hospitals
…Priors
(β ,...β
0
2
2
|
µ
,
σ
~
MVN(
µ
,
σ
I)
)
L
hj | P ~ P
P | α P0 ~ DP(α P0 )
• Prior on h assigns a random partition model for hospital-effects.
• Several estimates of the true clustering available from the MCMC algorithm.
• How to obtain a point estimate? (“label-switching” problem…)
MBC - Workshop on Model Based Clustering
Optimal partition under Binder’s loss function
See you at the poster …