Acronym for
binary digiT and the unit of
measurement for
variety ,
uncertainty ,
statistical entropy and
information , all of which are quantified in terms of the (average) number of binary digits required to count a given number of alternatives (
see degree of freedom ). Equivalent interpretations of this unit are the average number of
decisions required to exhaust a given number of alternatives, the average number of relays needed to represent a certain number, the average number of answers to yes-no questions necessary to select one out of a given number of objects. Thus the answer to a yes-or-no question conveys one bit of information. Two distinctions create four alternatives and not knowing which is desirable measures two bits of uncertainty. A Hollerith card with 12-by-80 places, each of which may be punched or left solid, can store 960 bits of information. More generally,
n equally likely alternatives correspond to log_2
n bits (
see law of requisite variety ). (
krippendorff )
