Probabilistic or Stochastic...?

prob•a•bil•is•tic
adj.
1. Of, relating to, or based on probabilism.
2. Of, based on, or affected by probability, randomness, or chance: "The Big Bang universe is . . . exemplified in the probabilistic and indeterminate interactions of the smallest known physical properties" (Frederick Turner).

sto•chas•tic
adj.
1. Of, relating to, or characterized by conjecture; conjectural.
2. Statistics
a. Involving or containing a random variable or variables: stochastic calculus.
b. Involving chance or probability: a stochastic stimulation.

Source: The Free Dictionary