Population Projection: Cases

Use the following information to answer the questions below:

                   Blue Earth County, MN--1980

          CURRENT  MALE   MALE   CURRNT FEMALE FEMALE  BIRTHRT

           MALE   SURVIV MIGRATN FEMALE SURVIV MIGRATN PER1OOO

COHORT      POP    RATE   RATE    POP    RATE   RATE   FEMALES

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75+        958    .523    .024    1811   .672   .093

70-74      610    .766   -.010     873   .876  -.010

65-69      943    .831   -.013     943   .916  -.011

60-64      830    .882   -.010    1145   .945  -.009

55-59     1065    .925    .010    1155   .963   .008

50-54     1071    .952   -.018    1128   .975  -.019

45-49     1047    .969   -.018    1051   .983  -.019

40-44      920    .983   -.097    1066   .989  -.061   18.2

35-39     1371    .989   -.109    1193   .993  -.070   18.2

30-34     1779    .993   -.402    1685   .996  -.465   69.4

25-29     2581    .993   -.115    2258   .997  -.304  140.4

20-24     3958    .992    .250    4211   .997   .298   72.4

15-19     2985    .992    .131    3226   .997   .201   30.1

10-14     1814    .995   -.034    1696   .998  -.051

5-9       1538    .998   -.118    1532   .999  -.083

0-4       2000    .998   -.038    1871   .998  -.012

M/F RATIO = 0.51

You can also get this data in a spreadsheet template here.

Blue Earth County population figures are heavily influenced by Mankato State University. Suppose the University were absent, and the 1980 data were adjusted to reflect the rates in surrounding rural counties:

          CURRENT  MALE   MALE   CURRNT FEMALE FEMALE  BIRTHRT

           MALE   SURVIV MIGRATN FEMALE SURVIV MIGRATN PER1OOO

COHORT      POP    RATE   RATE    POP    RATE   RATE   FEMALES

----------------------------------------------------------------

40-44                                                  21.3

35-39                                                  21.3

30-34                    -.207                 -.144   81.6

25-29                     .020                 -.103  172.3

20-24     2465           -.037    2393         -.052  170.6

15-19     2301           -.105    2179         -.065   36.9

Now how would you project the population of blue Earth County for the year 2000?

Suppose the University remained, but the fertility rate came more in line with neighboring communities (i.e., the college population showed the same childbearing patterns as others in the County). What effect would this change in fertility have on the population of Blue Earth County by the year 2000?

Suppose the Governor helped the city attract a major manufacturing plant, one that would hire 2500 new employees. Assume that unemployment is low enough that most of the new jobs will attract migrants to the area. Most of them will be 20-24 year-old males (40%) and females (20%). 20% will be 25-29 year-old males, 10% females age 25-29; 8% will be 30-34 year-old males, 2% females age 30-34. The average household will bring 0.7 spouses (adults of the same age cohort, opposite sex), 1.0 children age 0-4, 0.5 children age 5-9, and 0.25 children age 10-14. What effect will this single plant have on the population of Blue Earth County by the year 2000, assuming the newcomers follow the same fertility and migration patterns once they arrive?

Suppose medical science manages to extend life expectancy, changing the survival rate for the oldest cohort to 0.66 for men and 0.77 for women. What effect will this have on the population of Blue Earth County by the year 2000?