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Experiment ID
139
Pathogen
Cryptosporidium hominis
Cryptosporidium parvum
Contains Preferred Model
0
Reference
Risk Assessment for Cryptosporidium: A Hierarchical Bayesian Analysis of Human Dose Response Data
Host type
human
# of Doses
8.00
Μodel
exponential
k
5.26E-03
LD50/ID50
1.32E+02
Dose Units
oocysts
Response
infection
Agent Strain
Iowa isolate
Exposure Route
oral
Experiment Dataset
Description: 
Iowa isolate data [1]
Dose Infected Not infected Total
30 2 3 5
100 4 4 8
300 2 1 3
500 5 1 6
1000 2 0 2
1E+04 3 0 3
1E+05 1 0 1
1E+06 1 0 1

 

Goodness of fit and model selection
Model Deviance Δ Degrees 
of freedom		 χ20.95,1 
p-value		 χ20.95,m-k 
p-value
Exponential 3.07 2 7 3.84 
0.157		 14.1 
0.879
Beta Poisson 1.07 6 12.6 
0.983
Exponential is preferred to beta-Poisson; cannot reject good fit for exponential.

 

Optimized k parameter for the exponential model, from 10000 bootstrap iterations
Parameter MLE estimate Percentiles
0.5% 2.5% 5% 95% 97.5% 99.5%
k 5.26E-03 2.25E-03 2.75E-03 3.08E-03 1.03E-02 1.19E-02 1.60E-02
ID50/LD50/ETC* 1.32E+02 4.33E+01 5.80E+01 6.72E+01 2.25E+02 2.52E+02 3.08E+02
*Not a parameter of the exponential model; however, it facilitates comparison with other models.

Parameter histogram for exponential model (uncertainty of the parameter)

Exponential model plot, with confidence bounds around optimized model

References

  1. Messner, M. J., Chappell C. L., & Okhuysen P. C. (2001).  Risk Assessment for Cryptosporidium: A Hierarchical Bayesian Analysis of Human Dose Response Data. Water Research. 35, 16.