This paper surveys results of a research program investigating human judgments of imprecise probabilities under sample space ignorance. The framework used for comparisons with human judgments is primarily due to Walley [9, 10]. The five studies reported here investigate four of Walley's prescriptions for judgment under sample space ignorance, as well as assessing the impact of the number of observations and types of events on subjective lower and upper probability estimates. The paper concludes with a synopsis of future directions for empirical research on subjective imprecise probability judgments.
Keywords. Human judgment, uncertainty, ambiguity, vagueness, probability.
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Michael Smithson and Thomas Bartos