autocorrelation


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autocorrelation

[¦ȯd·ō‚kär·ə′lā·shən]
(electronics)
A technique used to detect cyclic activity in a complex signal.
(statistics)
In a time series, the relationship between values of a variable taken at certain times in the series and values of a variable taken at other, usually earlier times.
References in periodicals archive ?
From the literature survey, applications of wavelet and autocorrelation to the raw vibration signals were widely used in bearing fault diagnosis [16, 17].
The autocorrelation represents the process of correlation of a signal with itself.
For a signal x(t) , the autocorrelation function can be obtained by the formula 1 [16].
An autocorrelation is of Lag 1 when the correlation between [y.sub.t] and [y.sub.t-1] is calculated; Lag 2 when the correlation between [y.sub.t] and [y.sub.t-2] is calculated; Lag k, when the correlation between [y.sub.t] and [y.sub.t-k] is calculated
While figure 2-B provides the statistical significance of districts in terms of local indicators of spatial autocorrelation; with cumulatively 19 statistically significant districts from the rest, at the level of <0.05.
In addition to the test of kurtosis to diagnose the status of the channel, we propose the use of other tests instead of the kurtosis: the autocorrelation and the Likelihhod Ratio goodness of fit (LLR GoF) tests.
For this step autocorrelation (ACF) and partial autocorrelation (PACF) were plotted to determine whether the data is stationary or not.
Therefore, the autocorrelation test was done to test the whiteness on residual of the models.
The detection methods are based on spectral correlation [7-9] and the methods for parameter estimation are based on autocorrelation [10, 11].
Therefore, based on the existing aviation accident data, this paper used GIS spatial analysis model, including nuclear density analysis, hotspot analysis, and spatial autocorrelation analysis, to study the temporal and spatial characteristics of aviation accidents and rank the potential accidents airports around the hot spots.
However, as the time interval becomes smaller, the presence of autocorrelation in the data increases.
In addition, we explore whether the spatial autocorrelation (Koenig and Knops, 1998; Overmars et al., 2003) can influence the resulting elevational gradient in species richness.