Confidence contours (68/95%) in the Ω_m − σ₈ plane for various combinations of datasets (CMB, X-ray or SZ clusters) and assumptions (T08 or D16 mass function, A_T − M left free or fixed to the Planck cluster calibration, cf. Sect. 3.1). For the clusters-only cases, additional uniform priors on Ω_m and H₀ have been applied (see Sect. 4.1 for details). On this figure, the “CMB” and “CMB + X-ray clusters” contours are virtually identical.