Determining Spurious Correlation between Two Variables with Common Elements: Event Area-Weighted Suspended Sediment Yield and Event Mean Runoff Depth

Peng Gao, Lianjun Zhang

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Spurious correlation is a classic statistical pitfall pervasive to many disciplines including geography. Although methods of calculating the spurious correlation between two variables possessing a common element in the form of sum, ratio, or product have been developed for a long time, controversial assertions on whether the spurious correlation should be treated or ignored are still prevalent. In this study, we examined this well-known but intriguing issue using the data representing two nonindependent variables, event area-weighted suspended sediment yield (SSYe) and event mean runoff depth (h). By transferring the correlation between SSYe and h to that between suspended sediment transport rate (Qs) and water discharge (Q), we developed a new method of determining whether Qs is truly correlated to Q. The method involves calculating coefficients of spurious correlation ((Formula presented.)) and the associated “pure” spurious correlation ((Formula presented.)), a hypothesis test, and regression between (Formula presented.) and (Formula presented.). Our analysis showed that (1) there exists a true correlation between SSYe and h and (2) the spurious correlation is strongly related to the variability of the variables. We then proposed a general rule stating that the apparent spurious correlation between two variables could be ignored if the two have a true causal relation. At last, we distinguished the difference between spurious correlation and spurious reference.

Original languageEnglish (US)
Pages (from-to)261-270
Number of pages10
JournalProfessional Geographer
Volume68
Issue number2
DOIs
StatePublished - Apr 2 2016

Keywords

  • sediment transport
  • spurious correlation
  • spurious inference

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Earth-Surface Processes

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