WOLFRAM|DEMONSTRATIONS PROJECT

Hidden Periodicity in Quality Control Records

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data points n
300
simulated data's approximate μ and σ
μ
0.
σ
1.
seed
0
use seed for a repeatable random sequence
periodicity
none
5
7
15
10
6
3
8
4
9
show autocorrelation function plot
Many fluctuating industrial quality control charts appear as random time series but may be hiding an underlying periodicity. While such periodicity can be practically undetectable in the raw record, it is clearly revealed in an autocorrelation plot. This is shown with simulated random records having different periodicities.