We study positive weight functions ω(z) on the unit disk D such that D |f (z)| p ω(z) dA(z) < ∞ if and only ifˆD (1 − |z| 2) p |f ′ (z)| p ω(z) dA(z) < ∞, where f is analytic on D and dA is area measure on D. We obtain some conditions on ω that imply the equivalence above, and we apply our conditions to several important classes of weights that have appeared in the literature before. D |f (z) − f (0)| p dA α (z) ∼ˆD(1 − |z| 2) p |f ′ (z)| p dA α (z) for f ∈ H(D). See [6, 14]. It is then natural to ask for conditions on finite positive Borel measures µ on D such that D |f (z) − f (0)| p dµ(z) ∼ˆD(1 − |z| 2) p |f ′ (z)| p dµ(z)