halvesone

Halvesone (symbol hs) is a fictional unit of information magnitude used in hypothetical discussions of probability and decision making. It is defined to measure the change in informational content when the likelihood of a binary outcome is halved, within a reference distribution. This article treats halvesone as a fictional concept for illustrative purposes; it is not an established scientific unit.

Formal definition: Let p be the probability of the correct outcome under a binary decision. The halvesone value H(p) is defined as -log2(p) measured in halvesone units, so that halving p to p/2 increases information content by exactly one halvesone. Consequently, one halvesone corresponds to one bit of surprisal under this convention. The unit is unitless in that it is a ratio of information measures, not a physical dimension.

History and usage: The concept of halvesone originated in thought experiments regarding pedagogy for information theory, and appears in fictional or hypothetical texts as a way to illustrate how information content scales with probability. In those settings, researchers compare experiments by reporting results in halvesones rather than bits, sometimes to emphasize the effect of halving probabilities rather than absolute probabilities.

See also: bits, information theory, surprisal, log-likelihood, probability.