Table 2 Widely used copula functions.

From: Impact of global crisis events on the dependence and risk spillover between gold and crude oil: a regime-switching copula approach

Name

Copula CDF

Parameter scale

Gaussian

\(C(u,v)={{{\Phi }}}_{2}\left({{{\Phi }}}^{-1}(u),{{{\Phi }}}^{-1}(v);\rho \right)\)

ρ (−1, 1)

t

\({C}_{\nu}(u,v)={T}_{\nu}\left({T}_{\nu }^{-1}(u),{T}_{\nu }^{-1}(v);\rho \right)\)

ρ (−1, 1)

Clayton

\({C}_{Cl}(u,v;\theta )={\left({u}^{-\theta }+{v}^{-\theta }-1\right)}^{-\frac{1}{\theta }}\)

θ (0, + )

Gumbel

\({C}_{G}(u,v;\alpha )=\exp \left(-{\left[{\left(-\ln u\right)}^{\alpha }+{\left(-\ln v\right)}^{\alpha }\right]}^{\frac{1}{\alpha }}\right)\)

\(\alpha \in \left[1,+\infty \right)\)

  1. Note: Φ and Φ2 are the cumulative distribution functions (CDFs) of the standard normal distribution and the bivariate standard normal distribution, respectively. Tν represents the CDF of the bivariate t distribution with ν degrees of freedom.