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Applications of technical risk assessment in Food Industry by R Milano R Days 27th September 2012
Applications of technical risk assessment in Food Industry by R
Milano R Days 27th September 2012
Contents
2
Scope: technical & logistic risks – two examples
Scenario: VEE development model and risks impacts
Technical risk assessment challenges
Statistical methods and tools: Bayesian inference
References
Code examples
Procedural steps
Conclusions
Scope: decision support @ milestones
3
E.g.: Critical performance requirements target not fully achieved with
real or potential claim risk:
Scope: decision support @ milestones
4
E.g.: Time-limited potentially perceived defectiveness related to
delayed delivery of concurrent development.
Project A
Project B
3-7 out
of
10.000
0-1 out
of
10.000
Delayed
deliverable
Vee model: Development process model & issues/problems impact
5
User
Needs
System
requirements
System
architecture
Sub-system
components
design
System
integration
System
verification
System
validation
Components
testing
System usage
System
maintenance
System
upgrade
Technical risk assessment: challenges:
6
Technical Performance Measures statistical models: Normal, LogNormal, Gamma, Exponential, Weibull, Poisson,
Binomial
Un-complete, non-homogeneous information
zero-defects case, potential risk
Last minute, high pressure, decision support
Coherent meth. Applications & effective communication
Business, logistic and technical viewpoints.
Statistical methods and tools:
7
Frequentistic classical inference
Structured designs
Non-parametric statistic
Bayesian inference
Montecarlo simulations
…
Bayesian Approach:
How to update the opinions on the base of the new evidence No risk assessment without historical data knowledge. It fits the human learning by experience logic It foster communication barriers overcoming
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Previous
info
Inference
on
Actual data
Posterior
information
Knowledge(t+1)
New evidence:
likelihood
x
Prior information
Knowledge(t)
Reliability-type – reference*
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* http://www.itl.nist.gov/div898/handbook/apr/section4/apr47.htm
The conjugate concept
PT/2012-09-12 External / 10
* http://www.itl.nist.gov/div898/handbook/apr/section4/apr47.htm
The concept of the relations between the probability density function and its conjugate is key to the evaluation of the uncertainty reduction and the computation of the risk to reach the target
Informed simplification without trivialization.
Code References 1/3
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Code References 2/3:
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Code References 3/3:
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Reference list:
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Bayesian Computation with R, Second Edition. Jim Albert. Springer. 2009
Bayesian Inference and Computation, research papers Rasanji C. Rathnayake , 2010
Southern Illinois University Carbondale
LearnBayes, Coda, MCMCpack, king MCMC,… packages documentation
Assessing Product Reliability NIST Engineering handbook (with code)
Introduzione ai metodi bayesiani – Milotti, Universitá di Trieste
Manuale di Statistica Soliani, http://www.dsa.unipr.it/soliani/soliani.html
Bayesian Inference and Decision Theory, Kathryn Blackmond Laskey George Mason University 2011
Probabilistic Risk Analysis, foundations and methods T. Bedford, R. Cooke Cambridge 2001
MonteCarlo Applications in Systems Engineering A. Dubi Wiley and Sons 2000
Risk Analysis, a quantitative guide IInd edition 2006, D. Vose Wiley
MonteCarlo Bayesian System Reliability and MTBF confidence assessment, Air force flight dynamics
laboratory, 1978
Procedural steps:
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Define objectives and background
Identify risk analysis problem dimensions
Re-use previous studies
or
Screen-out suitable references: (theory, assumptions, code, examples)
Select suitable reference(s)
Validate reference(s) vs. problem statement and background
Tailor reference code vs. specific problem statement
Verify code (sensitivity analysis, parallel verifications)
Use
Communicate
Document
Generalize and develop interface if worth
Keep updated
Integrate with other codes
Conclusions:
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The technical risk assessment in liquid food industry is like a boiling pot:
It never boils if you look at it
The content pours out as soon as you answer the phone.
You never find the pot holder when needed
One handle swings when you lift it.
There is never a free safe place to lay down.
Who cleans when everything is finished?
…
The door bell shall ring again the next time it boils.
What a piece of luck there is R!
