Short-Cut Methods of Forecasting City Population

Foxecasting City Population by the Ratio Method

“…T H E "ratio method" has won wide acceptance among city planners, demographers, marketing analysts, and social statisticians as the best shortcut means currently available for forecasting city population, yet water supply and sanitary engineers seem to be relatively unaware of its existence. The ratio method has been described, tested, and applied by many authorities since its early, rudimentary use in the mid-1920's (1)(2)(3)(4)(5)(6), so that its value has become widely known to population forecasters. Despite this great popularity, however, a review of seven representative texts (7)(8)(9)(10)(11)(12)(13) in the fields of water supply and sanitary engineering disclosed seven accounts-all enthusiastic-of the long discredited analogy (comparative) method; six, of the equally outmoded geometric method; five, of arithmetic projection; two, of logistic extrapolation; four, of miscellaneous methods; and none, of the ratio method.…”

“…Other techniques of projecting ratios include the fitting and extrapolation of a logistic curve, the use of a "least squares" arithmetic projection based on data for three or more census years, and simple arithmetic or geometric extrapolation of the trend revealed by the two most recent censuses. These methods appear with varying frequency in recent literature (2,6).…”