scope:

INTRODUCTION

The ability to produce reliable statistical calculations for mean, standard deviation, and variance is a requirement of good laboratory practice. A key aim within the clinical laboratory is to minimize errors in order to give the best possible results for a patient. The variability of results is measured by a descriptive term called the standard deviation. It represents a special point on the general Normal curve where data distribution begins to spread out.

This document provides the following items for the laboratorian and manufacturer:

• The definitions and formulas for mean, standard deviation, and variance

• A method to check the accuracy of standard deviation computations. The document contains sample problems with solutions for the statistics of standard deviation and variance.

• Rules and procedures for the generation of a computed answer with respect to the number of significant figures and the correct procedures for rounding the data.