Panic attack symptoms are a common reaction. Other anxiety disorders include: agoraphobia, separation anxiety disorder and substance/medication-induced anxiety disorder involving intoxication or withdrawal or medication treatment.
Statistics and Probability Dictionary. Select a term from the dropdown text box. The online statistics glossary will display a definition, plus links to other related web pages. Select term: Variance. The variance is a numerical value used to indicate how widely individuals in a group vary. If individual observations vary greatly from the group mean, the variance is big; and vice versa. It is important to distinguish between the variance of a population and the variance of a sample.
For a single variate having a distribution with known population mean , the population variance , commonly also written , is defined as. (1) where is the population mean and denotes the expectation value of . For a discrete distribution with possible values of , the population variance is therefore. (2) whereas for a continuous distribution, it is given by. (3) The variance is therefore equal to the second central moment .