Statistical Uncertainty

Scientists make measurements of the natural world — first to describe it and then to understand the fundamental laws that govern its operation. There is uncertainty, however, due to the limited accuracy and precision of the measurements and to the variability that occurs in nature. Scientists use statistical methods to help interpret their measurements and quantify the amount of uncertainty. Statistics involves analyzing numerical data from a specific set of observations in order to make broader generalizations about the natural world.

The following pages discuss details of four aspects of statistical uncertainty:

• Measurement Errors are due to the physical limitations of the sensors and techniques used to make the measurements.
• Natural Variability is the range in values of naturally occurring parameters in biological and other natural systems.
• False Positives and False Negatives are errors associated with making a decision.
• Statistical versus Biological Significance compares the results of statistical analyses within the range of natural variability.