A fair statement of the odds that a rational, well-informed person would give or take for the outcome of an experiment. The experiment may be unique and not rationally understood (precluding both theoretically sound predication and empirical experience). The formulation is applicable to experiments that have been carried out but the outcome unknown. (For instance, a certain statement about the sex of the foetus early in pregnancy is established but perhaps not accessible until amniocentesis can be done.) unlike personal probably, the subjective probability should be the same from all competent counselors in possession of the same evidence.