Population sensitivity of acute flaccid paralysis and environmental surveillance for serotype 1 poliovirus in Pakistan: an observational study

Table 2 Bayes factors for each model applied to AFP and environmental surveillance data of serotype 1 WPV in Pakistan, January 2010 – August 2015 . A Bayes factor greater than 1.00 indicates an improved model fit when compared to the baseline model

Assumption for AFP surveillance	Assumption for environmental surveillance	Number of parameters	Model evidence	Bayes Factor
One value	One value	4	− 502.9	NA
Linear increase with log₁₀(incidence)	One value	5	− 493.9	9*
One value	Linear increase with catchment size	5	−504.5	−1.6
Linear increase with log₁₀(incidence)	Linear increase with catchment size	6	− 495.3	7.6*
One value	Quadratic relationship with catchment size	6	− 505.5	−2.6
Linear increase with log₁₀(incidence)	Quadratic relationship with catchment size	7	− 496.3	6.6*
One value	Mixed effects structure (no association with catchment size)	6	− 491.4	11.5*
Linear increase with log₁₀(incidence)	Mixed effects structure (no association with catchment size)	7	− 481.3	21.6*

The starred models have an improved fit to the data in comparison to the simplest model and the best-fitting model is highlighted in bold

ISSN: 1471-2334