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Mardia's circular-linear correlation

Source: R/stats-circular.R
circularLinearCorrelation.Rd

The association between an angular variable (e.g. a coupling angle or relative phase) and a linear one (e.g. speed, force, a clinical score). Symmetric under rotation of the angle.

Usage

circularLinearCorrelation(theta, x, units = c("degrees", "radians"))

Arguments

theta

Numeric angular variable.

x

Numeric linear variable (same length as theta).

units

"degrees" (default) or "radians" for theta.

Value

an htest: the circular-linear correlation r (estimate), the test statistic n * r^2 ~ chi-square(2) and its p.value.

References

Mardia KV (1976); Zar JH (1999) eq. 27.19.

See also

circularSummary()

Examples

set.seed(3); th <- runif(60, 0, 360); y <- cos(th * pi / 180) + rnorm(60, 0, 0.3)
circularLinearCorrelation(th, y)$estimate            # strong association
#>        r 
#> 0.932514