  We discuss the value of the cosmological constant as recovered from CMB and
LSS data and the robustness of the results when general isocurvature initial
conditions are allowed for, as opposed to purely adiabatic perturbations. The
Bayesian and frequentist statistical approaches are compared. It is shown that
pre-WMAP CMB and LSS data tend to be incompatible with a non-zero cosmological
constant, regardless of the type of initial conditions and of the statistical
approach. The non-adiabatic contribution is constrained to be < 40% (2sigma
c.l.).
