Assessing the value of information to design site investigation and construction quality assurance programs - Risk and Reliability in Geotechnical Engineering - page 513

Figure 13.40 Prior probability that fraction of contaminated soil is less than 0.05 in subareas of oil refinery.

Cost

Remediation

C R

Use available data

No future problem

$ 0

No
remediation

P ( H £ 1/20) = p ′ i

C R : $ Cost of
remediation

Future problem

3 × C R

P ( H > 1/20) = 1- p ′ i

Subarea i :
H ~ Beta(a′ i , b′ i )
P ( H < 1/20) = p ′ i

X : Number of
contaminated samples

Remediation

X = 0

C R

Initiate
sampling
program

X = x

No future problem

$ 0

H | X = x ~ Beta(a′′ i , x , b′′ i , x )
P ( H <1/20| X = x ) = p ′′ i , x

No
remediation

n samples P ( H £ 1/20| X = x ) = p ′ i

X = n

Future problem

3 × C R

P ( H > 1/20| X = x ) = 1- p ′ i

Figure 13.41 Preposterior decistion tree to assess value of information in obtaining additional soil samples
from a subarea of oil refinery.