We propose that synchronicities — defined formally in URB #416 as events crossing the LCC detection threshold CEMERICK — obey a Matthew Effect: those who receive and act on them develop higher base rates, while those who suppress or dismiss them develop lower base rates. This produces stratified populations with *person-specific base rates* for synchronistic experience. Far from crumbling Bayesian statistics, this *completes* it: standard Bayes assumed a universal base rate P (E) for all observers; Person-Specific Bayes (PSB) adds the observer index p, making the framework more precise and more powerful. We formalize this as the PSB theorem, identify testable predictions, and catalog available databases for empirical validation. The seismic implication: the apparent disagreement between skeptics and psi-researchers about synchronicity base rates is not a conflict about the same data — they are *both right*, because they are measuring different populations with genuinely different rates.
Brandon Charles Emerick (Tue,) studied this question.