The number of people whom Familypedia knows to have been alive in any part of a particular calendar year. (User:rtol may be able to state that more precisely, e.g. does it count a full 1.0 for anyone born or dying at any time in that year? — Robin Patterson (Talk) 14:29, June 6, 2010 (UTC)


  1. Proportions such as Mortality, which use "People" as if it were the known population, will be overstated, because "People" does not include people known to have existed but for whom either of the vital dates is missing. Even people dying in a given year are not counted for that year, even though they were clearly alive in part of that year. A good argument for trying to give estimates. Birth years are generally easier to estimate than death years but must sometimes be wild guesses.
  2. Can never be totally certain for any year even where birth and death dates are stated, particularly for the four-and-a-bit centuries after the introduction of the Gregorian calendar and before it was "universally" adopted, because someone whose birth we know only as "December 1749" (somewhere in the British Empire) might have been born in December 1749 or in January 1750 (N.S.), and our conversion program cannot say which unless it knows more about which part of December. If all we know is "1749 in England", we have only a 70% chance of being right in Gregorian terms if we say "1749". Never mind other calendars such as Chinese, though we can probably convert from them with similarly imperfect certainty. — Robin Patterson (Talk) 14:29, June 6, 2010 (UTC)