Descriptive statistics

Most students will be familiar with the concept of laboratory measurements, particularly in physical chemistry. As chemists we read burettes, thermometers, stop watches, pH meters, and a multitude of other instruments and the read values are fed into equations to calculate quantities such as concentrations, enthalpy changes, rate constants and electrode potentials, to name a few. Normally we get only one chance to perform a given experiment, although we may take multiple readings in some cases. 

Textbooks, however, are full of well established quantities whose values we take for granted, e.g. the gas constant, the electronic charge and the acceleration due to gravity. A moment's thought will suggest that these values were not arrived at as a result of a single laboratory session of two to three hours!