Variance Calculations: Difference between revisions

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== Parameters ==  
== Parameters ==  


n: number of values
$n$: number of values


== Table of Algorithms ==  
== Table of Algorithms ==  
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| [[Naïve algorithm ( Variance Calculations)|Naïve algorithm]] || 1940 || $O(n)$ || $O({1})$ auxiliary || Exact || Deterministic ||   
| [[Naïve algorithm ( Variance Calculations)|Naïve algorithm]] || 1940 || $O(n)$ || $O({1})$ || Exact || Deterministic ||   
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| [[Two-pass algorithm ( Variance Calculations)|Two-pass algorithm]] || 1940 || $O(n)$ || $O({1})$ auxiliary || Exact || Deterministic ||   
| [[Two-pass algorithm ( Variance Calculations)|Two-pass algorithm]] || 1940 || $O(n)$ || $O({1})$ || Exact || Deterministic ||   
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| [[Welford's Online algorithm ( Variance Calculations)|Welford's Online algorithm]] || 1962 || $O(n)$ || $O({1})$ auxiliary || Exact || Deterministic || [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.302.7503&rep=rep1&type=pdf Time]
| [[Welford's Online algorithm ( Variance Calculations)|Welford's Online algorithm]] || 1962 || $O(n)$ || $O({1})$ || Exact || Deterministic || [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.302.7503&rep=rep1&type=pdf Time]
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| [[Weighted incremental algorithm ( Variance Calculations)|Weighted incremental algorithm]] || 1979 || $O(n)$ || $O({1})$ auxiliary || Exact || Deterministic || [https://dl-acm-org.ezproxy.canberra.edu.au/doi/10.1145/359146.359153 Time]
| [[Weighted incremental algorithm ( Variance Calculations)|Weighted incremental algorithm]] || 1979 || $O(n)$ || $O({1})$ || Exact || Deterministic || [https://dl-acm-org.ezproxy.canberra.edu.au/doi/10.1145/359146.359153 Time]
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| [[Chan's algorithm Parallel Implementation ( Variance Calculations)|Chan's algorithm Parallel Implementation]] || 1979 || $O(log n)$ || $O({1})$ per processor || Exact || Parallel || [http://i.stanford.edu/pub/cstr/reports/cs/tr/79/773/CS-TR-79-773.pdf Time]
| [[Chan's algorithm Parallel Implementation ( Variance Calculations)|Chan's algorithm Parallel Implementation]] || 1979 || $O(\log n)$ || $O({1})$ per processor || Exact || Parallel || [http://i.stanford.edu/pub/cstr/reports/cs/tr/79/773/CS-TR-79-773.pdf Time]
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[[File:Variance Calculations - Time.png|1000px]]
[[File:Variance Calculations - Time.png|1000px]]
== Space Complexity Graph ==
[[File:Variance Calculations - Space.png|1000px]]
== Time-Space Tradeoff ==
[[File:Variance Calculations - Pareto Frontier.png|1000px]]

Latest revision as of 09:08, 28 April 2023

Description

Given a set of n (real/integer) numbers, compute the variance (sample or population). Of interest is streaming algorithms and numerical stability.

Parameters

$n$: number of values

Table of Algorithms

Name Year Time Space Approximation Factor Model Reference
Naïve algorithm 1940 $O(n)$ $O({1})$ Exact Deterministic
Two-pass algorithm 1940 $O(n)$ $O({1})$ Exact Deterministic
Welford's Online algorithm 1962 $O(n)$ $O({1})$ Exact Deterministic Time
Weighted incremental algorithm 1979 $O(n)$ $O({1})$ Exact Deterministic Time
Chan's algorithm Parallel Implementation 1979 $O(\log n)$ $O({1})$ per processor Exact Parallel Time

Time Complexity Graph

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