Investopedia contributors come from a range of backgrounds, and over 25 years there have been thousands of expert writers and editors who have contributed. Robert Kelly is managing director of XTS ...

Knowing an average is not enough to properly describe a data set. You also need a measure of how dispersed the data is. Values that are packed closely together display greater consistency than those ...

THE dispersion formula of Kramers and Heisenberg is valid for an atomic system the dimensions of which are small compared with the wave-length of incident light. For very short waves the scattering ...