From the end of Chapter 1 ("Signals for Honolulu") of Roberta Wohlstetter's Pearl Harbor:

... the job of collecting data is intimately bound up with the job of evaluating it. A sensitive collector knows what sounds to select out of a background of noise, and his presentation of the significant sounds is in itself a major first step in evaluation. For perception is an activity. Data are not given; they are taken. Moreover, the job of lifting signals out of a confusion of noise is an activity that is very much aided by hypotheses and by a background of knowledge much wider than the technical information we have considered so far. ...

^z - 2017-10-26