Standard deviation
| Syntax: | s = STDEV(x)s = STDEV(w,x) |
The STDEV function only accepts one or two vector arguments.
If only one vector is entered, the function returns the standard deviation of that vector's data. If two
vectors are entered, the first vector holds the weights and the second vector holds the data. The result is
always a scalar value.
Suppose that x is a vector with N elements.
A weight vector, w, may be entered as the first argument. The
length of w is assumed to also be N. If no weights are entered,
defaults to
1, for
.
Define the total weight:
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The mean value,
, is
defined by
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The variance,
, is
defined by
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The standard deviation,
,
is defined by ![]()
Examples
Suppose X = [1;2;3;4;5;6;7;8;9;10], then A = STDEV(X) returns
scalar A with the value 3.02765.
Suppose W = [1;1;1;5;5;5;5;1;1;1], then A = STDEV(W,X) returns
scalar A with the value 2.09293.