POPULATION FORECASTING.pptx

A small ppt on population forecasting

1. POPULATION FORECASTING

2. Population forecasting is a method by which we calculate the future population of any city or region at the interval of n number of decade (10 year) years. DEFINATION

3. ARITHMETIC INCREASE METHOD METHODS OF POPULATION FORECASTING INCREMENTAL INCREASE METHOD GEOMETRIC INCREASE METHOD DECREASE RATE OF INCREASE METHOD

4. GRAPHICAL PROJECTION METHOD METHODS OF POPULATION FORECASTING MASTER PLAN METHOD COMPARATIVE GRAPHICAL METHOD LOGISTIC CURVE METHOD

5. 01 ARITHMETICAL INCREASE METHOD

6. ARITHMETICAL INCREASE METHOD Simplest method This method is Used for calculation of population of large cities, which having constant development. Not used for small cities, because it gives lower value. In this method we consider that the rate of change of population ( dP /dt = C) of a city is approximately constant C.

7. Arithmetical Increase Method Formula P n = P o + nx ̄, where, P o - last known population P n - population (predicted) after 'n' number of decades, n - number of decades between P o and P n and, x̄ - the rate of population growth.

8. Arithmetical Increase Method Example Problem YEAR POPULATION 1930 25000 1940 28000 1950 34000 1960 42000 1970 47000 Question: With the help of the common data find the population for the year 2020 using the arithmetic increase method.

9. YEAR POPULATION INCREASE 1930 25000 - 1940 28000 3000 1950 34000 1960 42000 8000 1970 47000 5000 SOLUTION: STEP 1 : Find the increase in population each decade Step 2: Find the average rate of increase of population (x̄) x̄ = (3000+6000+8000+5000)/4 x̄ = 22000/4 x̄ = 5500 Step 3: Find the number of decades (n) between the last known year and the required year n = 5 (5 decades elapsed between 1970 and 2020) Step 4: Apply the formula P n = P o + nx ̄, P [2020] = P [1970] + (5 * 5500) P [2020] = 47000 + 27500 P [2020] = 74,500 . Therefore, population at 2020 will be 74,500.

10. 02 GEOMETRICAL INCREASE METHOD

11. GEOMETRICAL INCREASE METHOD The increase rate of population is not constant in this method, the percentage increase in population is considered. This method is suitable for small cities or new developing town for a few decade years, because it gives higher value by percent increase.

12. Geometrical Increase Method Formula P n = P o [1 + (r/100)]^n , where, P o - last known population, P n - population (predicted) after 'n' number of decades, n - number of decades between Po and Pn and, r - growth rate = (increase in population/initial population) * 100 (%).

13. Geometrical Increase Method Example Problem YEAR POPULATION 1930 25000 1940 28000 1950 34000 1960 42000 1970 47000 Question: With the help of the common data find the population for the year 2020 using the Geometrical increase method.

14. YEAR POPULATION INCREASE GROWTH RATE 1930 25000 - - 1940 28000 3000 (3000/25000) X 100 = 12% 1950 34000 6000 (6000/28000) X 100= 21.4% 1960 42000 8000 (8000/34000) X 100= 23.5% 1970 47000 5000 (5000/42000) X 100= 11.9% SOLUTION: STEP 1 : Find the increase in population each decade and find the growth rate Step 3: Find the average growth rate (r) using geometrical mean. r = ∜(12 * 21.4 * 23.5 * 11.9) r = 16.37 % Step 4: Find the number of decades (n) between the last known year and the required year n = 5 (5 decades elapsed between 1970 and 2020) Step 5: Apply the formula P n = P o [1 + (r/100)]^n P [2020] = P [1970] [1 + (16.37/100)]^5 P [2020] = 47000[1.1637]^5 P [2020] = 1,00,300. Therefore, population at 2020 will be 1,00,300.

15. 03 INCREMENTAL INCREASE METHOD

16. INCREMENTAL INCREASE METHOD This method is the combination of arithmetic increase and incremental increase method.

17. Incremental Increase Method Formula P n = (P o + nx ̄) + ((n(n+1))/2)* ȳ, where, Po - last known population, P n - population (predicted) after 'n' number of decades, n - number of decades between P o and P n , x̄ - mean or average of increase in population and, ȳ - algebraic mean of incremental increase (an increase of increase) of population.

18. Incremental Increase Method Example Problem YEAR POPULATION 1930 25000 1940 28000 1950 34000 1960 42000 1970 47000 Question: With the help of the common data find the population for the year 2020 using the Incremental increase method.

19. YEAR POPULATION INCREASE INCREMENTAL INCREASE 1930 25000 - - 1940 28000 3000 - 1950 34000 6000 6000-3000=3000 1960 42000 8000 8000-6000=2000 1970 47000 5000 5000-8000= -300 SOLUTION: STEP 1 : Find the increase in population each decade and find the incremental increase i.e., increase of increase Step 3: Find x̄ and ȳ as average of Increase in population and Incremental increase values respectively. x̄ = (3000+6000+8000+5000)/4 x̄ = 5500 ȳ = (3000+2000-3000)/3 ȳ = 2000/3 Step 4: Find the number of decades (n) between the last known year and the required year n = 5 (5 decades elapsed between 1970 and 2020) Step 5: Apply the formula P n = (P o + nx ̄) + ((n(n+1))/2)* ȳ, P [2020] = (P[1970] + nx ̄) + ((n(n+1))/2)* ȳ P [2020] = 47000 + (5 * 5500) + (((5 * 6)/2) * (2000/3)) P [2020] = 84,500. Therefore, population at 2020 will be 84,500 .

20. 04 DECREASING RATE OF GROWTH METHOD

21. DECREASING RATE OF GROWTH METHOD This method is adopted for a town which is reaching saturation population, where the rate of population growth is decreasing. In this method, an average decrease in growth rate (S) is considered.

22. Decreasing Rate of Growth Method Formula P n = P (n-1) + ((r(n-1) - S)/100) * P (n-1) where, P n - population at required decade, P (n-1) - population at previous decade (predicted or available), r(n-1) - growth rate at previous decade and, S - average decrease in growth rate.

23. Decreasing Rate of Growth Method Example Problem YEAR POPULATION 1930 25000 1940 28000 1950 34000 1960 42000 1970 47000 Question: With the help of the common data find the population for the year 2020 using the decreasing rate of growth method.

24. YEAR POPULATION INCREASE IN POPULATION GROWTH RATE(r) DECREASE IN GROWTH RATE 1930 25000 - = - 1940 28000 3000 12% - 1950 34000 6000 21.4% 12-21.4=-9.4% 1960 42000 8000 23.5% 21.4-23.5=-2.1% 1970 47000 5000 11.9% 23.5-11.9+11.6% SOLUTION: Step 1: Find the increase in population. Step 2: Find the growth rate (r) as in the geometrical increase method. Step 3: Find the decrease in the growth rate.

25. Step 4: Find the average of decrease in growth rate(s). S = (-9.4-2.1+11.6)/3 S = 0.1/3 S = 0.03% Step 5: Apply the formula P n = P (n-1) + ((r (n-1) - S)/100) * P(n-1), and find the population at successive decade till the population at required data is arrived. P [1980] = P[1970] + ((r[1970] - S)/100) * P [1970] P [1980] = 47000 + ((11.9 - 0.03)/100) * 47000 P[ 1980] = 52579 P [1990] = P [1980] + ((r [1980] - S)/100) * P [1980] P [1990] = 52579 + ((11.87 - 0.03)/100) * 52579, here r[1980] is directly found as 11.9 - 0.03 i.e., r [1970] - S, which equals to 11.87. P [1990] = 58,804 Similarly, P[2020] could be found.

26. 05 GRAPHICAL PROJECTION METHOD

27. GRAPHICAL PROJECTION METHOD In this method, the population vs time graph is plotted and is extended accordingly to find the future population. It is to be done by an experienced person and is almost always prone to error.

28. Graphical Method Example Problem YEAR POPULATION A s per records 1970 170000 1980 191500 1990 203800 2000 215975 2010 251425 Question: Estimate the population in 2040

29. SOLUTION : Graphical Method

30. 06 COMPARATIVE GRAPHICAL METHOD

31. COMPARATIVE GRAPHICAL METHOD In this method, the population data of project is plotted along with past population data of number of town which have grown under the similar conditions. The curve of the city under consideration is extended carefully after studying the pattern of other cities.

32. 07 MASTER PLAN METHOD

33. MASTER PLAN METHOD This method is used for a completely planned city that is not meant to be developed in a haphazard manner.

34. 08 LOGISTIC CURVE METHOD

35. LOGISTIC CURVE METHOD The logistic curve method is suitable for regions where the rate of increase or decrease of population with time and also the population growth is likely to reach an ultimate saturation limit because of special factors. The growth of a city which follow the logistic curve, will plot as a straight line on the arithmetic paper with time intervals plotted against population in percentage of saturation.

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