IAI Actuarial Core Principles · Risk Modelling and Survival Analysis · Introduction to copulas
Which statement about Archimedean copulas is correct?
Archimedean copulas are constructed from a generator function φ, with C(u,v) equal to the inverse generator applied to φ(u) + φ(v). They need no correlation matrix or normal marginals, and different families show different tail dependence patterns.
- AThey are built from a generator function φ, with C(u,v) = φ^(-1)(φ(u) + φ(v))Correct
- BThey can only be defined in two dimensions and never extended further
- CThey always have the same tail dependence in both tails
- DThey are constructed from a correlation matrix only
- They require the marginal distributions to be normal
Explanation
An Archimedean copula is defined through a decreasing convex generator φ with φ(1)=0, as C(u,v)=φ^(-1)(φ(u)+φ(v)). Tail behaviour differs by family (Clayton lower, Gumbel upper), and they can be extended to higher dimensions with restrictions. Marginals can be any distributions.
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