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Experiment ID
79, 80
Pathogen
Salmonella typhi
Agent Strain
Quailes
Contains Preferred Model
Yes
Reference
Hornick, R. ., Woodward, T. ., McCrumb, F. ., Snyder, M. ., Dawkins, A. ., Bulkeley, J. ., … Corozza, F. . (1966). Study of induced typhoid fever in man. I. Evaluation of vaccine effectiveness. Transactions of the Association of American Physicians, 79, 361-367. Retrieved from https://pubmed.ncbi.nlm.nih.gov/5929469/
Exposure Route
oral (in milk)
Response
disease
Host type
human
# of Doses
8.00
Dose Units
CFU
Μodel
beta-Poisson
a
1.75E-01
N50
1.11E+06
LD50/ID50
1.11E+06
Description
Model data for S. Typhi (Quailes) in humans
Dose Disease No disease Total
1000 0 14 14
1E+05 28 76 104
1E+05 32 84 116
1E+07 15 15 30
1E+07 16 16 32
1E+08 8 1 9
1E+09 4 0 4
1E+09 40 2 42

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value 		χ20.95,m-k 
p-value
Exponential 419 406 7 3.84 
0 		14.1 
0
Beta Poisson 13.8 6 12.6 
0.0321
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
0.5% 2.5% 5% 95% 97.5% 99.5%
α 1.75E-01 1.21E-01 1.32E-01 1.39E-01 2.23E-01 2.34E-01 2.58E-01
N50 1.11E+06 5.13E+05 6.10E+05 6.72E+05 2.00E+06 2.28E+06 2.95E+06

 

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