Draft Population Projections for Anguilla over the period 2002 to 2011
Introduction
Population projections are simply that, projections. They are not forecasts of what the population is expected to be but rather a mechanical model based upon assumptions about birth, death and migration rates. The number of births minus deaths gives the natural rate of increase of the population. Then numbers emigrating is subtracted from numbers immigrating to result in a net migration figure, which is added to the population adjusted for the natural rate of increase. Thus the projections are very sensitive to the assumptions made about migration into and out of Anguilla.
In countries with larger populations than Anguilla, population projections are given for each single year of age broken down by sex and are done for each year. Since Anguilla has no experience with population projections and their use, and given the wide fluctuations in death, birth and migration rates from year to year, these projections are based upon 5-year intervals and 5-year age groups broken down by sex to smooth out fluctuations in birth and death rates.
Births
The number of births that occurs is dependant upon the fertility rate of the population. In turn the overall fertility rate is dependent upon the number of women who are in their child-bearing years. For example, if there is a greater proportion of women in the age groups when women tend to have children, then there is a tendency for the country to have a higher fertility rate. Age specific fertility rates are expressed per 1,000 of women in the specific age group and the child-bearing years are normally considered to be 15 to 44 years.
The chart above shows that women in all age groups, with exception of 25 – 29 year olds have been experiencing slight growth in their fertility rates over the past 8 years. In general, however, they do fluctuate widely due to the small number of births in each age group. Therefore for the purposes of these projections, the average 3 year age fertility rates over the past 3 years have been used to project births over the next 10s.
Fertility rates among teenagers are relatively high and may decline over the next 10 years as family planning programmes are targeted to teenagers. However for the purposes of these projections no change has been assumed over the next ten years.
The following tables shows the number of births by age of mother historically and also the number projected over the ten year period assuming the three year average age specific fertility rates. Note over the period 2002 –6 the total number of births projected is 907 and over the 2007-11 period the number of projected births is 970.
Number of Births by Age of Mother, 1995 to 2002 and projections for 2002-6 and 2007-11
Year
|
Total |
19 & under |
20-24 |
25-29 |
30-34 |
35-39 |
40&over |
|
1995 |
167 |
18 |
50 |
51 |
33 |
12 |
3 |
|
1996 |
161 |
23 |
40 |
44 |
33 |
14 |
7 |
|
1997 |
169 |
24 |
49 |
54 |
28 |
12 |
2 |
|
1998 |
155 |
27 |
29 |
38 |
34 |
20 |
7 |
|
1999 |
176 |
29 |
42 |
43 |
35 |
22 |
5 |
|
2000 |
193 |
37 |
48 |
42 |
43 |
17 |
6 |
|
2001 |
182 |
30 |
56 |
44 |
25 |
20 |
7 |
|
2002 |
169 |
23 |
42 |
41 |
40 |
16 |
7 |
|
|
|
Projections – average births
per year
|
|
|
|||
|
2002-06 |
182 |
30 |
49 |
42 |
36 |
18 |
7 |
|
2007-11 |
194 |
36 |
59 |
42 |
32 |
17 |
8 |
Death
Deaths and death
rates are dependent upon the age structure of the whole population, not just
women. The chart below shows how death
rates increase with age and have bee declining slightly in recent years among
the older age groups.
For the purposes of these population projections it was
decided to use the average death rates over the past 5 years by five year age
group to forecast the total deaths. The rates are shown in the table below:
|
Age groups |
Deaths over 5 years 1998-2002 |
Death Rates over 5 years using
2001 Population |
||||
|
Male |
Female |
Total |
Male |
Female |
Total |
|
|
0 - 4 |
3 |
1 |
4 |
0.005714 |
0.001825 |
0.003728 |
|
5 - 9 |
- |
1 |
1 |
0 |
0.002037 |
0.001007 |
|
10 - 14 |
- |
1 |
1 |
0 |
0.001745 |
0.00088 |
|
15 - 19 |
2 |
3 |
5 |
0.004193 |
0.00611 |
0.005165 |
|
20 - 24 |
3 |
3 |
6 |
0.008 |
0.007264 |
0.007614 |
|
25 - 29 |
3 |
3 |
6 |
0.006818 |
0.006928 |
0.006873 |
|
30 - 34 |
4 |
2 |
6 |
0.008097 |
0.00396 |
0.006006 |
|
35 - 39 |
4 |
1 |
5 |
0.00789 |
0.001876 |
0.004808 |
|
40 - 44 |
5 |
1 |
6 |
0.011655 |
0.002212 |
0.00681 |
|
45 - 49 |
7 |
2 |
9 |
0.019231 |
0.005714 |
0.012605 |
|
50 - 54 |
7 |
3 |
10 |
0.029661 |
0.012931 |
0.021368 |
|
55 - 59 |
7 |
5 |
12 |
0.042169 |
0.031847 |
0.037152 |
|
60 - 64 |
7 |
7 |
14 |
0.048611 |
0.04375 |
0.046053 |
|
65 - 69 |
14 |
9 |
23 |
0.08805 |
0.070866 |
0.08042 |
|
70 - 74 |
19 |
13 |
32 |
0.231707 |
0.100775 |
0.151659 |
|
75 - 79 |
19 |
22 |
41 |
0.292308 |
0.244444 |
0.264516 |
|
80 - 84 |
23 |
29 |
52 |
0.442308 |
0.58 |
0.509804 |
|
85 + |
30 |
50 |
80 |
0.625 |
0.735294 |
0.689655 |
|
Total |
157 |
156 |
313 |
0.027896 |
0.026887 |
0.027384 |
Using these death rates, the projected deaths are shown in the table below.
Deaths by Age Group, Actual Figures for 1998 to 2001 and Projections for annual averages for 2002-6 and 2007-11
|
Age |
1998 |
1999 |
2000 |
2001 |
2002-6 |
2007-11 |
|
0 - 4 |
1 |
1 |
0 |
0 |
1 |
1 |
|
5 - 14 |
0 |
1 |
1 |
0 |
0 |
0 |
|
15-29 |
1 |
3 |
3 |
5 |
4 |
4 |
|
30-44 |
2 |
2 |
6 |
3 |
3 |