Population Pyramids

Figure 4-8: Population Pyramid, United States (1975)
-10,00% -8,00% -6,00% -4,00% -2,00% 0,00% 2,00% 4,00% 6,00% 8,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
10,00%
Female %
Male %

Figure 4-9: Population Pyramid, United States 2000
-10,00% -8,00% -6,00% -4,00% -2,00% 0,00% 2,00% 4,00% 6,00% 8,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
10,00%
Female %
Male %

Figure 4-10: Population Pyramid, Somalia (1975)
-10,00% -8,00% -6,00% -4,00% -2,00% 0,00% 2,00% 4,00% 6,00% 8,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
10,00%
Female %
Male %

Figure Figure 4-11: Population Pyramid, Somalia (2000)
-10,00% -8,00% -6,00% -4,00% -2,00% 0,00% 2,00% 4,00% 6,00% 8,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
10,00%
Female %
Male %

-6,00%
Figure 4-12: Population Pyramid, North Carolina PUMA 0500 (Northwest rural area) 1990
-4,00% -2,00% 0,00% 2,00% 4,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
6,00%
Female %
Male %

-6,00%
Figure 4-13: Population Pyramid, North Carolina PUMAs 1901, 1902, 1903 (Wake County,
1990)
-4,00% -2,00% 0,00% 2,00% 4,00%
80+
75-79
70-74
65-69
60-64
55-59
50-54
45-49
40-44
35-39
30-34
25-29
20-24
15-19
10-14
5-9
0-4
6,00%
Female %
Male %

Data for Pyramids?
• Age / Sex tables
• American Community Survey
• Access via American Fact Finder

Forecasting and Extrapolation
• Estimates, Projections and Forecasts
• Estimates
– An indirect measure of a present or past condition that can be directly measured
– Example: estimating town population based on water/sewer hookups

Forecasting and Extrapolation
• Estimates, Projections and Forecasts
• Projections
– Conditional (if/then)
– If current population growth continues, Boone will run out of water/sewer capacity

Forecasting and Extrapolation
• Estimates, Projections and Forecasts
• Forecasts
– A judgmental statement of what is most likely to occur in the future
– Assumes consideration of alternative assumptions

Forecasting and Extrapolation
• Looking into a crystal ball
– But with some guidance
• This will involve “curve-fitting”

Forecasting Population (aggregate)
Population Linear Curve Estimation: Leon County, FL
160,0
140,0
120,0
100,0
80,0
60,0
40,0
20,0
0,0
1940 1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015