Let { A( t)} be a sequence of bounded nonnegative matrices [each with Perron root λ( t)] satisfying a condition of uniform primitivity and having nonzero entries bounded away from 0. In a generalization of a result on powers of primitive matrices it is shown that if the matrices A( t) vary slowly enough (i.e., ‖ A( t+1)− A( t)‖⩽ ε for all t and some small ε), then, as soon as the entries p i,j ( t) of the backward product A( t) A( t−1), ⋯, A(1) are positive, the ratios p i, j ( t)/ p i, j ( t−1) are equal to λ( t)+ h i, j ( t), where for all t 0 each h i,j ( t 0) is small in a precisely quantified manner: the larger t 0 is and the slower the probability-normed Perron vectors V( t) of A( t) have changed in the recent past preceding t 0, the smaller h i,j ( t 0) will be. (Other similar results are derived.) The resulting approximation p i, j ( t)/ p i, j ( t−1)≈ λ( t) is illustrated with two numerical examples.