# Measurement

## Overview

### Description

Making accurate measurements is an important skill in all branches of science. Quantitative measurements provide scientists with a way to communicate information and allow comparison of results from different experiments and studies. It is therefore important to have a common system of measurement that can be understood by everyone. All measurements contain inherent error; thus, all measurements contain some uncertainty. The number of significant figures used in a measurement describes the sensitivity of the equipment used to make the measurement. Units can be converted from one system or type of unit to another through dimensional analysis, a method of making comparisons between measurements that are part of different systems or use different units.

### At A Glance

• Units of measurement must be based on objective, physical, unchanging standards.
• The International System of Units (SI), abbreviated from French Système Internationale d'Unités, is used by all branches of science. This system provides a standardized set of units that can be used by scientists to ensure precise and objective definitions.
• Matter can be described by its mass, weight, and volume. Mass is the amount of matter in an object. Weight is the force of gravity acting on an object. Volume is the three-dimensional space occupied by a gas, a liquid, or a solid.
• Common temperature scales are the Fahrenheit scale, the Celsius scale, and the Kelvin scale. Unlike the Fahrenheit and Celsius scales, the Kelvin scale has no negative temperatures, and no degree symbol is used when temperatures are reported in kelvins.
• Accuracy and precision are characteristics that describe the exactness of a measurement, or closeness to the true value of the measured quantity.
• Measurements contain inherent error that must be reported.
• Different laboratory tools have different levels of precision.
• The number of significant figures to report depends on the type of calculation being performed.
• Units can be converted from one type to another through dimensional analysis, a method of making comparisons between measurements that are part of different systems or use different units.