Table 1

Formulas for computing partial variances and partial correlations


Definition
True value
Estimate

Covariance matrix:
cov(Xk, Xl) = σkl
Σ = (σkl)
S = (skl)
Concentration matrix:
Ω = Σ-1
Ω = (ωkl)

Variances:
var(Xk) = σkk = Math
σkk
skk
Partial variances
var(Xk|Xk) = Math = Math = Math
Math
Math
Correlations:
corr(Xk, Xl) = ρkl = σkl (σkk σll)-1/2
P = (ρkl)
R = (rkl)
Partial correlations:
corr(Xk, Xl|Xk, l) = Math
Math
Math

Index i runs from 1 to n (sample size), and indices k and l run from 1 to p (dimension). A tilde denotes a "partial" quantity.

Opgen-Rhein and Strimmer BMC Systems Biology 2007 1:37   doi:10.1186/1752-0509-1-37