org.eclipse.jetty.util.statistic

## Class SampleStatistic

• ```public class SampleStatistic
extends Object```
SampledStatistics

Provides max, total, mean, count, variance, and standard deviation of continuous sequence of samples.

Calculates estimates of mean, variance, and standard deviation characteristics of a sample using a non synchronized approximation of the on-line algorithm presented in Donald Knuth's Art of Computer Programming, Volume 2, Seminumerical Algorithms, 3rd edition, page 232, Boston: Addison-Wesley. that cites a 1962 paper by B.P. Welford that can be found by following the link http://www.jstor.org/pss/1266577

This algorithm is also described in Wikipedia at http://en.wikipedia.org/w/index.php?title=Algorithms_for_calculating_variance§ion=4#On-line_algorithm

• ### Field Summary

Fields
Modifier and Type Field and Description
`protected AtomicLong` `_count`
`protected AtomicLong` `_max`
`protected AtomicLong` `_total`
`protected AtomicLong` `_totalVariance100`
• ### Constructor Summary

Constructors
Constructor and Description
`SampleStatistic()`
• ### Method Summary

Methods
Modifier and Type Method and Description
`long` `getCount()`
`long` `getMax()`
`double` `getMean()`
`double` `getStdDev()`
`long` `getTotal()`
`double` `getVariance()`
`void` `reset()`
`void` `set(long sample)`
`String` `toString()`
• ### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`
• ### Field Detail

• #### _max

`protected final AtomicLong _max`
• #### _total

`protected final AtomicLong _total`
• #### _count

`protected final AtomicLong _count`
• #### _totalVariance100

`protected final AtomicLong _totalVariance100`
• ### Constructor Detail

• #### SampleStatistic

`public SampleStatistic()`
• ### Method Detail

• #### reset

`public void reset()`
• #### set

`public void set(long sample)`
• #### getMax

`public long getMax()`
Returns:
the max value
• #### getTotal

`public long getTotal()`
• #### getCount

`public long getCount()`
• #### getMean

`public double getMean()`
• #### getVariance

`public double getVariance()`
• #### getStdDev

`public double getStdDev()`
• #### toString

`public String toString()`
Overrides:
`toString` in class `Object`