Question

What are the differences between these chemistry vaiables: variance, standard deviation, uncertainty, and tolerance? Do any of these have the same definition?

Answer 1

Variance-The number of thermodynamic variables, such as temperature and pressure, required to specify a state of equilibrium of a system, given by the phase rule; the degrees of freedom of a system.

Standard deviation-Standard deviation measures how widely spread data points are.The standard deviation, s, is a statistical measure of the precision for a series of repeated measurements. The advantage of using s to quote uncertainty in a result is that it has the same units as the experimental data.

Uncertainty-Uncertainty as used in chemistry means the range of possible values within which the true value of the measurement lies.

Tolerance-A tolerance is an allowable, but non-deliberate, amount of variation from a physical quantity.

Variance and standard deviation have same definition.The variance and the closely related standard deviation are measures of how spread out a distribution is. In other words, they are measures of variability.