A nanogram (ng) is a unit of mass in the metric system, equal to one billionth (10-9) of a gram (g). The gram is a base unit of mass in the International System of Units (SI), making the nanogram a ...

A principal component analysis of a correlation matrix treats all variables as equally important. A principal component analysis of a covariance matrix gives more weight to variables with larger ...

If you were stuck on a desert island and could only take one piece of workout equipment, make it a pair of dumbbells (followed closely by an adjustable weight bench). I’ve been lifting weights ...