# STDEV

## Purpose:

Calculates the sample standard deviation
of a series.

## Syntax:

STDEV(series, first,
points)

series |
- |
Optional. Any series or expression resulting
in a series. Defaults to the current Window. |

first |
- |
Optional. An integer, the first point to include
in the calculation of the standard deviation. Defaults to 1. |

points |
- |
Optional. An integer, the number of points
to include in the standard deviation calculation. Defaults to the number
of points from first to the end
of the series. |

## Returns:

A real.

## Example:

stdev(gsin(100,0.01), 5, 20)

returns the standard deviation value 0.2403611.

## Example:

stdev(W3, 5, 10)

returns the standard deviation of 10 points
of the series in Window 3 starting with the 5th point.

## Remarks:

STDEV computes the sample standard deviation
defined as:

where the arithmetic mean is defined as:

STATS provides
both STDEV and MEAN.

NaN values are ignored.

COLSTDEV
can be used to determine the standard deviations of each column in a table.

See STD
to calculate the population standard deviation.

## See Also:

COLSTDEV

KURTOSIS

MEAN

MOVSTD

RMS

ROWSTDEV

SKEW

STATS

STATSUM

STD

STDERR