4.1 Introduction

Statistics in the ORA laboratory may be used to describe and summarize the results of sample analysis in a concise and mathematically meaningful way. Statistics may also be used to predict properties (ingredient, acidity, quantity, dissolution, height, weight) of a contaminant or of a regulated product as a whole based on measurements made on a subset, or sample, of the contaminant or product. All statistical concepts are ultimately based on mathematically derived laws of probability. Understanding statistical concepts will allow the ORA analyst to better convey analytical results with the maximum amount of assurance as to quality of the data.

By profession and training, the ORA laboratory analyst is motivated to carry out measurements precisely, and to report results that contain the maximum amount of useful information. Proper application of statistics gives this ability, while allowing for the fact that there is inherent error (both random and determinate) in virtually every laboratory measurement made.

This section is not meant to be an in-depth reference for the myriad ways that statistics could be applied in the laboratory, but rather as a general guide for situations commonly encountered in the ORA laboratory. The section also gives guidance on various aspects of data presentation and verification.