Understanding nonsense correlation between (independent) random walks in finite samples

  • Consider two independent random walks. By chance, there will be spells of association between them where the two processes move in the same direction, or in opposite direction. We compute the probabilities of the length of the longest spell of such random association for a given sample size, and discuss measures like mean and mode of the exact distributions. We observe that long spells (relative to small sample sizes) of random association occur frequently, which explains why nonsense correlation between short independent random walks is the rule rather than the exception. The exact figures are compared with approximations. Our finite sample analysis as well as the approximations rely on two older results popularized by Révész (Stat Pap 31:95–101, 1990, Statistical Papers). Moreover, we consider spells of association between correlated random walks. Approximate probabilities are compared with finite sample Monte Carlo results.

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Author:Uwe HasslerORCiDGND, Mehdi Hosseinkouchack
URN:urn:nbn:de:hebis:30:3-637223
DOI:https://doi.org/10.1007/s00362-021-01237-0
ISSN:1613-9798
Parent Title (English):Statistical papers
Publisher:Springer
Place of publication:Berlin ; Heidelberg [u.a.]
Document Type:Article
Language:English
Date of Publication (online):2021/05/06
Date of first Publication:2021/05/06
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2022/10/20
Tag:Coin tossing; Concordance; Discordance; Maximum length of association
Volume:63
Issue:1
Page Number:15
First Page:181
Last Page:195
Note:
Open Access funding enabled and organized by Projekt DEAL.
HeBIS-PPN:502475455
Institutes:Wirtschaftswissenschaften / Wirtschaftswissenschaften
Dewey Decimal Classification:3 Sozialwissenschaften / 33 Wirtschaft / 330 Wirtschaft
5 Naturwissenschaften und Mathematik / 51 Mathematik / 510 Mathematik
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0