Population Forecasting Methods

Arithmetical Increase Method

• Assumes a constant increase in population over time.
• Formula: Pr = Po + nx where:
  • Pr = future population
  • Po = initial population
  • n = number of decades
• Ideal for older, established cities with limited expansion opportunities.

Geometric Increase Method

• Assumes a constant growth rate percentage.
• Formula: Pr = Po (1+r/100)^n where:
  • Pr = future population
  • Po = initial population
  • r = growth rate per decade
  • n = number of decades
• Best suited for young, rapidly expanding cities.

Incremental Increase Method

• Assumes varying average increase of population between decades.
• Formula: Pr = Po + nx + (n^2)y where:
  • Pr = future population
  • Po = initial population
  • n = number of decades
  • x = average increase per decade
  • y = average increase of the increase per decade
• Applicable for both old and new cities.

Decreasing Rate of Growth Method

• Assumes a downward trend in the growth rate.
• Used when growth rate is nearing saturation, resulting in decreased growth.

Comparative Graphical Method

• Assumes similar growth trends among smaller cities.
• Involves plotting population growth graphs of comparable cities for analysis and comparison.

Logistic Curve Method

• Assumes limited land area for community growth.
• Formula: P = Ps / (1 + ml(nt)) with components:
  • Ps = saturation population
  • Po = initial population
  • P1 = population at time t1
  • P2 = population at time t2
  • n = growth rate
  • m = slope of the growth curve at time 0
• Utilizes concepts of population dynamics and saturation.

Population Forecasting Methods

• Arithmetical Increase Method

  • Assumes a constant population growth rate.
  • Formula to forecast: ( P_r = P_o + nx )
  • Ideal for established cities with limited expansion opportunities.

• Geometric Increase Method

  • Assumes fixed population growth rate every decade.
  • Forecasting formula: ( P_r = P_o(1 + r/100)^n )
  • Suitable for young, rapidly developing cities with ample growth potential.

• Incremental Increase Method

  • Assumes variable average growth rates across decades.
  • Formula used: ( P_r = P_o + nx + \frac{1}{2}y )
  • Applicable to all types of cities, both old and new.

• Decreasing Rate of Growth Method

  • Assumes a downward trend in population growth rates.
  • Best used when a population is nearing saturation, indicating slowing growth.

• Comparative Graphical Method

  • Based on characteristics of smaller, similarly growing cities.
  • Involves graphing and comparing growth patterns of related communities.

• Logistic Curve Method (by C.F. Verhulst)

  • Assumes limited land availability for future growth.
  • Population forecast formula: ( P = \frac{P_s}{1 + mli^{(nt)}} )
  • Where:
    • ( P_s ) = Population at saturation
    • ( P_o ) = Initial population
    • ( n ) = Rate of increase
    • ( t ) = Time
    • ( m ) = ( \frac{P_s - P_o}{P_o} )
    • ( l ) = ( \frac{P_2 - P_1}{P_1 - P_o} )
  • Useful for populations with clear growth limits.

Explore the various methods of population forecasting, focusing on the Arithmetical and Geometric Increase Methods. Understand key formulas and assumptions associated with each method, and learn their applications in different urban contexts. This quiz will enhance your knowledge of demographic analysis techniques.