Statistical Aspects of the Microbiological Examination of Foods

Chapter 1: Introduction

• • Abstract

Chapter 2: Some basic statistical concepts

• • Abstract
• • Populations
• • Lots and samples
• • Average sample populations
• • Statistics and parameters
• • The central limit theorem

Chapter 3: Frequency distributions

• • Abstract
• • Types of frequency distribution
• • Statistical probability
• • The binomial distribution (σ2 < μ)
• • The Normal distribution
• • The Poisson distribution (σ2 = μ)
• • The negative binomial distribution (σ2 > μ)
• • Relationships between the frequency distributions
• • Transformations

Chapter 4: The distribution of microorganisms in foods in relation to sampling

• • Abstract
• • Random distribution
• • Regular distribution
• • Contagious (heterogeneous) distributions
• • Effects of sample size

Chapter 5: Statistical aspects of sampling for microbiological analysis

• • Abstract
• • Attributes and variables sampling
• • Binomial and trinomial distributions
• • Precision of the sample estimate
• • Acceptance sampling by attributes
• • Acceptance sampling by variables
• • Some statistical considerations about drawing representative samples
• • Addendum

Chapter 6: Errors associated with preparing samples for analysis

• • Abstract
• • Laboratory sampling errors
• • Calculation of the relative dilution error
• • Effects of gross dilution series errors on the derived colony count

Chapter 7: Errors associated with colony count procedures

• • Abstract
• • Specific technical errors
• • Pipetting and distribution errors
• • Limiting precision and confidence limits of the colony count
• • General technical errors
• • Comparability of colony count methods
• • Overall error of colony count methods

Chapter 8: Errors associated with quantal response methods

• • Abstract
• • Dilution series and most probable number counts
• • Multiple test dilution series
• • Special applications of multiple-tube dilution tests
• • Other statistical aspects of multistage tests

Chapter 9: Statistical considerations of other methods in quantitative microbiology

• • Abstract
• • Direct microscopic methods
• • Indirect methods

Chapter 10: Measurement uncertainty in microbiological analysis

• • Abstract
• • Accuracy, trueness and precision
• • Measurement uncertainty
• • Sampling uncertainty

Chapter 11: Estimation of measurement uncertainty

• • Abstract
• • The ‘generalised uncertainty method’ or ‘bottom-up’ procedure
• • The ‘top-down’ approach to estimation of uncertainty
• • Analysis of variance
• • Measurement of intermediate reproducibility
• • Estimation of uncertainty associated with quantal methods
• • Use of reference materials in quantal testing

Chapter 12: Statistical process control using microbiological data

• • Abstract
• • What is statistical process control?
• • Tools for statistical process control
• • Shewhart’s control charts for variables data
• • CUSUM charts
• • The moving windows average
• • Control charts for attribute data
• • Recent developments in statistical process control

Chapter 13: Validation of microbiological methods for food

• • Abstract
• • The stages of method development
• • What is validation?
• • Validation of qualitative methods
• • Validation of quantitative methods
• • Future directions

Chapter 14: Risk assessment and microbiological criteria for foods

• • Abstract
• • Risk assessment and food safety objectives
• • Microbiological criteria
• • The relevance of measurement uncertainty to MC
• • Conclusions