unrepeatable event

Terms from Statistics for HCI: Making Sense of Quantitative Data

Sometimes we can repeat an identical event multiple times, for example repeatedly tossing a coin. However, some events are unrepeatable, for example, the weather on 3rd January 2020. Crucially once such an event has occurred it is, by definition, not ontologically random – its state is already determined. However, it may still be epistemologically random, unknown to you, and hence you may sometimes still treat it as having probabilistic or statistical properties.

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