Optimization Output for Exp. 83 | QMRA wiki

Basic information

Experiment ID	83
Pathogen	Shigella flexneri
Agent Strain	2a (strain 2457T)
Contains Preferred Model	Yes
Reference	DuPont, H. L., Hornick, R. B., Snyder, M. J., Libonati, J. P., Formal, S. B., & Gangarosa, E. J. (1972). Immunity in Shigellosis. I. Response of Man to Attenuated Strains of Shigella. Journal of Infectious Diseases, 125, 1.
Exposure Route	oral (in milk)
Response	positive stool isolation

Detailed information

Host type

human

# of Doses

4.00

Dose Units

CFU

Μodel

beta-Poisson

a

2.65E-01

N50

1.48E+03

LD50/ID50

1.48E+03

Experiment Dataset

Description

**Model data for** **Shigella flexneri** **(2a, strain 2457T) in the human**
Dose	Positive stool isolation	No positive stool isolation	Total
180	6	30	36
5000	33	16	49
1E+04	66	21	87
1E+05	15	9	24

**Goodness of fit and model selection**
Model	Deviance	Δ	Degrees of freedom	χ²_0.95,1 p-value	χ²_0.95,m-k p-value
Exponential	169	160	3	3.84 0	7.81 0
Beta Poisson	8.73	160	2	3.84 0	5.99 0.0127
Neither the exponential nor beta-Poisson fits well; beta-Poisson is less bad.

**Optimized parameters for the beta-Poisson model, from 10000 bootstrap iterations**
Parameter	MLE estimate	Percentiles
Parameter	MLE estimate	0.5%	2.5%	5%	95%	97.5%	99.5%
α	2.65E-01	1.47E-01	1.74E-01	1.87E-01	3.82E-01	4.09E-01	4.70E-01
N₅₀	1.48E+03	5.60E+02	7.33E+02	8.26E+02	2.55E+03	2.78E+03	3.38E+03

Parameter scatter plot for beta Poisson model ellipses signify the 0.9, 0.95 and 0.99 confidence of the parameters.

beta Poisson model plot, with confidence bounds around optimized model

References