PHY.8:4.1 - Specify the observable and how it will be used

Name the physical quantity, spatial extent and observation interval. Decide whether the work needs a value at one time, a time average, a response after an intervention or the chance of crossing a threshold. These uses can require different statistics from the same system.

Relate the observable to the retained microscopic description. In a classical account, write it as a function of the state, or of a history when the measurement integrates over time. Include a measurement response when it changes the answer. MMP.7 constructs the probability law of the recorded outcome from a subject law and a recording procedure.

Separate physical variation from uncertainty about a fixed parameter. A rate that changes among preparations, an unknown common rate and a fresh independent rate for each constituent describe different arrangements. Keep a fixed unknown parameter explicit unless a probability law over it is warranted for the intended inference.