CMP.9:4.1 - Separate the target, access and output

State whether the result is a random object, a subset, an expectation, an event probability, or another statistic. For sampling, specify the target probabilities, item identity, replacement rule and any order requirement. For estimation, define the quantity, such as μ=E_p[f(X)], before designing how X will be obtained.

Describe access: an indexed collection, a one-pass stream, evaluable weights, a generative operation, or neighbors of a current state. An evaluable probability density does not necessarily provide a cheap sampler. An unnormalized density does not supply its normalization constant.

If the inputs describe observations, MMP.7 supplies the relevant recording and inclusion law. Sampling uniformly from recorded rows remains different from sampling uniformly from the people, events or other objects those rows describe.