The discount factor preference to avoid delay must be more than multiplictavely linear in the delay time passed, or one would not use this term to describe the utility function. In theory this attribute is analytically distinct from other reasons to want something sooner, such as interest rates; the bounded rationality problem of remembering how and when to consume the good later; or discounting of future events for reasons of opportunity, risk, or uncertainty (e.g., the chance of surviving to a later time).
There is evidence that human behavior exhibits great impatience which might be
modeled well by time preference and perhaps can perhaps be distinguished from
these other factors. So one may read references to empirical
observations of time preference, though as far as this editor can tell the
concept is quite theoretical and some jump is required to leave all other
explanations aside and link it directly to an observation.
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