On Wed, Apr 18, 2012 at 8:25 AM, Victor Stinner <victor.stin...@gmail.com> wrote:
> Ok ok, resolution / accuracy / precision are confusing (or at least > not well known concepts). Maybe not to us, but in fields like astronomy and mechanical engineering there are commonly accepted definitions: Resolution: the smallest difference between two physical values that results in a different measurement by a given instrument. Precision: the amount of deviation among measurements of the same physical value by a single instrument. Accuracy: the amount of deviation of measurements by a given instrument from true values. As usual there are issues of average vs. worst case, different resolution/precision/accuracy over the instrument's range, etc. which need to be considered in reporting values for these properties. A typical application to clocks would be the duration of one tick. If the clock ticks once per second and time values are reported in nanoseconds, the /resolution/ is *1 billion* nanoseconds, not *1* nanosecond. /Precision/ corresponds to the standard deviation of tick durations. It is not necessarily the case that a precise instrument will be accurate; if every tick is *exactly* 59/60 seconds, the clock is infinitely precise but horribly inaccurate for most purposes (it loses an hour every three days, and you'll miss your favorite TV show!) And two /accurate/ clocks should report the same times and the same durations when measuring the same things. I don't really care if Python decides to use idiosyncratic definitions, but the above are easy enough to find (eg http://en.wikipedia.org/wiki/Accuracy_and_precision). _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
