This will return surprising values for most users, since the default of sample=false is rather unusual when speaking about variance.
Point is:
When using stats_variance($foo,TRUE) the sum is divided by n-1 while the default just divides it by n. So when you expect your variance to be lower you probable wanted to divide by n-1, therefore should set the second parameter =TRUE.
stats_variance
(PECL stats >= 1.0.0)
stats_variance — Returns the variance
Description
stats_variance
( array
$a
[, bool $sample = FALSE
] ) : float
Returns the variance of the values in a.
Parameters
-
a -
The array of data to find the standard deviation for. Note that all values of the array will be cast to float.
-
sample -
Indicates if
arepresents a sample of the population; defaults toFALSE.
Return Values
Returns the variance on success; FALSE on failure.
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Anonymous ¶
10 years ago
