geosciences (specifically in geophysics) it can be used to compute an autocorrelation seismic attribute, out of a 3D seismic survey of the underground. In medical ultrasound imaging, autocorrelation is used to visualize blood flow. In intertemporal portfolio choice, the presence or absence of autocorrelation in an asset's rate of return can affect the optimal portion of the portfolio to hold in that asset. Autocorrelation has been used to accurately measure power system frequency in numerical relays. Serial dependence Serial dependence is closely linked to the notion of autocorrelation, but represents a distinct concept (see Correlation and dependence). In particular, it is possible to have serial dependence but no (linear) correlation. In some fields however, the two terms are used as synonyms. A time series of a random variable has serial dependence if the value at some time in the series is statistically dependent on the value at another time . A series is serially independent if there is no dependence between any pair. If a time series is stationary, then statistical dependence between the pair would imply that there is statistical dependence between all pairs of values at the same lag . See also Autocorrelation matrix Autocorrelation technique Autocorrelation of a formal word Autocorrelator Correlation function Correlogram Cross-correlation Galton's problem Partial autocorrelation function Fluorescence correlation spectroscopy Optical autocorrelation Pitch detection algorithm Triple correlation CUSUM Cochrane–Orcutt estimation (transformation for autocorrelated error terms) Prais–Winsten transformation Scaled correlation Unbiased estimation of standard deviation References Further reading Mojtaba Soltanalian, and Petre Stoica. "Computational design of sequences with good correlation properties." IEEE Transactions on Signal Processing, 60.5 (2012): 2180–2193. Solomon W. Golomb, and Guang Gong. Signal design for good correlation: for wireless communication, cryptography, and radar. Cambridge University Press, 2005. Klapetek, Petr (2018). Quantitative Data Processing in Scanning Probe Microscopy: SPM Applications for Nanometrology (Second ed.). Elsevier. pp. 108–112 . Signal processing Time domain analysis