Early experience (1981-1982) with jittery position measurements in the CID (Collider Injector Development) and Sector 1 BPM (beam position monitor) system led us to ask whether the source of the observed noise was in the beam or in the BPM electronics. Prior to July, 1983, the signal from each BPM strip was individually processed. It occurred to us that the signal from each strip, when normalized by the sum of the signals from the two adjacent strips, made possible two independent measurements of the beam position in the plane containing the strip. When a single parameter is measured twice, one can look at the correlation of the measurements over a statistical sample of events. This will allow one to distinguish real parameter variations from measurement errors. In this case, a strong correlation in the two measurements from a given strip indicates beam jitter, whereas a lack of correlation indicates either that there is beam jitter in the normalizing plane or that the processing electronics is noisy in at least one channel. The five possible cases are illustrated. These plots are interpreted.