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Quantitative Risk Assessment Methods: Probabilistic Methods

This course is a hands-on introduction to Quantitative Methods for Food Safety Risk Analysis.  Quantitative methods use available data to describe (model) what is observed. These models have many uses. They are used to help explain observations, to make predictions about future events, or to provide decision-makers with tools to test the impact of alternative solutions to problems.  Analysis of a particular risk may require a series of models to describe various components, or steps, that impact on the risk. Typically, we call such a series of models a Quantitative Risk Assessment.

Quantitative risk assessment and quantitative methods generally can be very powerful, but require a strong command of the science and art of probabilistic methods. The results of a model can be very sensitive, for example, to the choice of distributions.  Using the wrong assumptions in a model can produce incorrect results. Incorrect results can lead to poor decisions, and to undesirable outcomes.

Quantitative methods are extremely useful tools.  This short course trains aspiring and experienced modelers in the use of probabilistic methods. The course uses @Risk™ software as the primary tool for advancing the student’s knowledge.  Successful participants will emerge from this course with basic @Risk™ skills and be prepared to advance into the Quantitative Methods: Model Building course.  @Risk™ software is provided to students for use in the course.  @Risk™ builds upon an intermediate knowledge of Microsoft Excel™ or other spreadsheet software.  Training in Excel™ is not provided by the JIFSAN program. Examine this file to self-assess your readiness to participate in this course.

The course is conducted in a computer teaching laboratory with a live instructor. Lectures describe various techniques.  Students then work individually or in groups to solidify their understanding of the lecture materials, and to begin to build quantitative skills.

Intermediate spreadsheet skills and knowledge of basic statistics are required.  We also strongly recommend Introduction to Food Safety Risk Assessment as a prerequisite to this course.

Resources:
Excel: There are web-based resources that provide introductory Excel 2003 training. Many such courses are available - some at no cost - like the one found at www.videoprofessor.com.

Basic Statistics: The quantitative methods courses do not require in-depth knowledge of statistics, but an understanding of basic terminology is necessary. There are web-based resources that provide information about basic statistics. Some examples include http://www.robertniles.com/stats and http://www.statsoft.com/textbook.

Overview of Topics

Probability Definitions

  • Probability Explained
  • Probability Rules
  • Discrete and Continuous Variables
  • Populations and Samples
  • Descriptive Statistics
  • Summarizing Data
  • Hypothesis Testing

Probability Distributions

  • Distributions Defined
  • Which Ones to Use in What Situations
  • Displaying Distributions

Choosing a Distribution

  • Empirical and theoretical distributions
  • Goodness of Fit and other Tests
  • Expert opinion

Monte Carlo

  • Monte Carlo Process
  • Applications
  • Reading and Reporting Results

Uncertainty and Variability

  • Taxonomy
  • What is Uncertain?
  • Systematic Approaches
  • Separating Variability and Uncertainty
  • Implications for Risk Management

Bootstrap Methods

  • What are They for
  • How to Use Them
  • Why They Work

Learning Objectives

After completing this course, students understand:

  • Where probabilities come from
  • Basic laws of probability and how to express it
  • Differences between discrete and continuous random variables
  • The importance of probability distributions in risk assessment
  • The kinds of parameters required to define a distribution
  • The most common discrete and continuous probability distributions
  • The difference between an analytical solution and a simulation
  • The two steps of the Monte Carlo process
  • The differences between variability and uncertainty
  • The reasons for separating uncertainty and variability
  • The steps in a bootstrap procedure
  • How to use @Risk™ software
This course meets a requirement of the JIFSAN Quantitative Track Certificate in Food Safety Risk Analysis

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JIFSAN
University of Maryland
0220 Symons Hall
College Park, MD 20742
E-mail: jquigley@umd.edu
Tel.: (301) 405-1696 Fax.: (301) 405-8390
 

 

University of Maryland JIFSAN