(1) A pattern of variation of a continuous variable continuous variable characterized by a symmetric bell-shaped curve.
(2) A data distribution that is bell shaped and symmetrical, the normal distribution is the basis for control chart and capability analysis.
(3) Normal distribution is the spread of information (such as product performance or demographics) where the most frequently occurring value is in the middle of the range and other probabilities tail off symmetrically in both directions. Normal distribution is graphically categorized by a bell-shaped curve, also known as a Gaussian distribution. For normally distributed data, the mean and median are very close and may be identical.
(4) The charting of a data set in which most of the data points are concentrated around the average (mean), thus forming a bell shaped curve.