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TEACHER
MANUAL
USPOP
UNITED STATES POPULATION STUDY
$
Developed By:
James Friedland, General Douglas MacArthur High School
Levittown, New York
Support Material By:
James Friedland
Programmed By:
James Friedland
Stuart Hollander, State University of New York
Stony Brook, New York
HUNTINGTON TWO COMPUTER PROJECT
Copyright <<)1973, State University of New York
13 June 1973
The work of the Huntington Two Computer Project is partially
supported by the National Science Foundation, Grant GW-5883.
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USPOP
TEACHER MANUAL
Table of Contents
I. Basic Information about the Unit ....
Il. Ynteoduction to the USPOP Unit .«..«
Lit. Veing tSrcr with Your Clase... 6 2 és
Eva Samp le Runs @ & ca e oe e @ a & e s e eS e
V. Key to Student Laboratory Investigations
VI. Additional Questions for Class Discussion
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I.
USPOP
TEACHER MANUAL
BASIC INFORMATION ABOUT THE UNIT
Subject Area:
Specific Topic:
Grade Level:
Coordinated
Computer Program:
Computer Language:
| Special Language
NN Features Used:
Abstract:
Biology, Ecology, Social Studies
Human Population Projection (USA)
10 = 12
USPOP
BASIC
TAB
USPOP is a highly flexible human population
model. In order to make student use easier,
the model has been oriented towards investiga-
tion of United States population projections.
Other applications are covered in the accom-
panying RESOURCE MANUAL.
The student can investigate the effects of
fertility, age of mother at birth of child,
sex ratio of the offspring and age-dependent
mortality on population size and structure.
Through use of 1970 census data, held in DATA
Statements, the student need enter only a few
of the required inputs.
If the student or teacher wishes to model sit-
uations other than that collected in the DATA
Statements, all or some of the required inputs
may have to be changed.
oe
II. INTRODUCTION TO THE USPOP UNIT
Students are deeply concerned with the effect of population growth, but
they often lack a solid body of information on which to base a solution. Lack
of information often leads to a sense of frustration and hopelessness.
USPOP uses simulation techniques as a stimulus to learning in the teach-
ing of many key demographic concepts involving population growth and age dis-
tribution. Students play the role of demographers projecting future popula-
tion trends. The STUDENT MANUAL leads the student through a series of five
investigations, each involving a single concept. The following concepts are
explored:
INVESTIGATION #1. Effect of fertility on population growth.
Fertility is seen to have a major impact on population growth.
INVESTIGATION #2. Effect of time of birth of first child on
the population-growth rate. Surprisingly, delaying the birth
of the first child can slow population growth, even if the
total number of offspring remains constant.
INVESTIGATION #3. Effect of reducing infant mortality.
Reducing infant mortality to the lowest level realistically
possible is seen to have only a minor impact on future popu-
lation size.
INVESTIGATIONS #4 and #5. Exploration of factors affecting
age distribution in a population. Again fertility is seen
as the major factor. Mortality is important, but it has
only a secondary effect on age distribution in the population.
III. USING USPOP WITH YOUR CLASS
A. Using USPOP as a Student Laboratory
We hope that this will be your primary use of USPOP. As different
teachers have access to different facilities, we have subdivided this
section according to teletype availability.
NOTE: USPOP is based on the latest information available at the time of
publication. Instructions have been included in the RESOURCE MANUAL
for updating USPOP as newer data becomes available. (See Section IV,
Part F,)
1) For those teachers having access to multiple-user systems
or those having their students working on their own time:
In cases where whole classes are using USPOP, we
Suggest that you have different groups of students
run each of the five student investigations, prepare
separate reports and then report back to the group
as a whole. After this, you may wish to carry out
some of the more sophisticated investigations found
in the RESOURCE MANUAL.
2) For those teachers with access to a single teletype only:
The great flexibility of USPOP presents a problem,
Each single investigation requires approxmiately
45 minutes for a single group of students. As a
result, for a given double laboratory period, a
maximum of from 6 to 8 students (working in teams
of 3 or 4) can make use of the computer. Below
are two alternative suggestions, from teachers in
a similar teaching situation, that have proven
successful:
a) Rotate your class through the USPOP investiga-
tions. While one or two groups are working on
USPOP, the other students can be carrying out
related traditional laboratory exercises; in
succeeding weeks let the other students use
the computer. USPOP materials have been
written in such a way so as to encourage
students to investigate independently.
b) Have the entire class explore a single USPOP
student investigation, but divide the labor.
Since each investigation is written in such
a way as to require from 4 to 8 trial runs
before a conclusion can be reached, you might
have each team of students make one or two
trial runs and prepare a report of results
for the entire class. This approach can be
even more instructive than the individual
approach, depending on the teacher's planning
and preparation of such tasks as organizing
each group's role, preparation of appropriate
summary tables for the collection of data,
and class preparation for the students’ roles
as demographers working as a team to solve a
complex problem in a minimum amount of time.
B.
studies.
Using USPOP for Project Work or Individualized Instruction
Most students should be encouraged to work with one or more of the
investigations in the STUDENT MANUAL before attempting more sophisticated
In the accompanying RESOURCE MANUAL, there are several advanced
investigations designed as open-ended experiments for the individual
Student.
Some students will want to use USPOP on their own.
is suggested that the student be given the background materials in the
RESOURCE MANUAL as a source of ideas for alternative investigations.
addition, the student must be aware of the USPOP model assumptions, also
found within the RESOURCE MANUAL.
C.
USPOP as a Classroom Tool
While designed as a laboratory simulation, USPOP may also be useful
to the teacher who neither has the time nor the computer facilities for
individual or group use of the program. Below are concepts that the
teacher might want to explore with an entire class by using USPOP.
NOTE:
1)
2)
one of USPOP's model assumptions.
to first try any original exercise outside of class.
requirements can be found in the RESOURCE MANUAL,
Population forecasting. Have your students read the
background materials in the STUDENT MANUAL and ask
them to predict changes in fertility, birth distribu-
tion, sex ratio of offspring, and mortality (especially
infant and old age). Prior to using USPOP in class,
discuss their decisions, and when agreement has been
reached, use USPOP to make the resultant projection.
Remember, it is wise to compare their projection with
a control. A good comparison might be conditions in
the future, should the 1970 conditions remain constant.
Zero population growth (ZPG). There are several inter-
esting (and surprising) aspects to this subject. You
may want to explore the following questions in some de-
tail: a) Will ZPG occur if fertility falls to 2 children
per family, and b) What changes might result in ZPG immed-
iately? For a general approach to this problem, see the
ADDITIONAL STUDENT PROJECTS Section in the RESOURCE
MANUAL.
In this case, it
owe
Due to USPOP's extreme flexibility, teachers may accidentally violate
For this reason, you are encouraged
A list of model
IV. SAMPLE RUNS
The runs below can be used to check the performance of USPOP once
it is loaded in your computer.
SAMPLE RUN #1 illustrates the many variations possible with USPOP.
Explanation of student responses are enclosed in boxes.
RUN #1
IF THE STUDENT
ANSWERS ANY OF
THESE QUESTIONS
WITH "1" (YES),
THEN THE COMPUTER
WILL READ IN 1970
DATA STORED WITHIN
THE PROGRAM.
DO YOU WANT REPORTS 1) EVERY 5 YEAR INTERVAL
OR 2) SELECTED YEARS 71.
YEAR AT START OF PROJECTION 71972
DO YOU ASSUME STANDARD FERTILITY C1=YESO=NQ) 71
WILL FERTILITY (1) STAY AT 2-45 | OR (2) ‘CHANGE SLOWLY
TO A NEW LEVEL 71
‘DO YOU ASSUME STANDARD BIRTH DISTRIBUTION (1=YES,9=NO)
DO YOU ASSUME STANDARD SEX RATIO C1=YES,9%=NO) 71
DO YOU ASSUME STANDARD MORTALITY (1=YES,9=NO) ?1
DO YOU ASSUME STANDARD POPULATION C1L=YESs@=NO) ?1
STUDENT HAS SELECTED
THE LONG REPORT.
REPORT:1)SHORT 2)LONG 3)GRAPH 4)CHANGE ASSUMPTIONS 5)END 72
YEAR 1979 POP= 284-8 MILLION FERTILITY 245
AGES FEMALES <-MILLIONS=> MALES PCTe TOTAL
G@- 4 Bed 8e7 Be
5..°.9 9-7 19.1 De 7
19 = 14 149-2 14-5 1961 ,
is = 2.9 9e4 9e7 904 IT GIVES POPULATION
24 = 24 8.5 Be6 S.3 IN THOUSANDS FOR
25 < 29 629 68 6e7 EACH COHORT AND
34 = 34 508 506 566 THE AGE DISTRI-
a3 = 39 507 5<5 5e4 BUTION IN THE
AA - 44 Gel 528 508 POPULATION.
45 - 49 602 5-9 5-9
a0 = 3&8 5-7 5-3 tes
22 * $9 5.2 407 48
64 - 64 46 4 42
65 = 69 307 3 303
70 = 74 3.2 223 2e7
BY TYPING 4, THE STUDENT IS ALLOWED
TO ALTER AN ASSUMPTION AND THEN
RESUME THE PROJECTION,
REPORT! ?4
WHAT DO YOU WANT TO CHANGE? |
1-FERTILITYs 2-BIRTH. DISTRIBUTION, 3-SEX RATIO.
A=-MORTALITY» 5 POPULATION ?4
CHANGE IN MORTALITY OCCURING IN FEMALES THIS ANSWER MEANS THAT THE
GROUPS (FROM AGEs TO AGE) 765394 STUDENT WISHES TO ALTER THE
GROUP CURRENT NEW VALUE MORTALITY RATES FOR FEMALES
DEATH/ 1499 BETWEEN THE AGES OF 65 AND 90.
65 = 69 789 266 THE COMMA BETWEEN THE TWO NUM-
70 + 74 #4Q164 2192 BERS IS IMPORTANT.
75 AND OVER 33763 72389
BY TYPING 9, THE STUDENT
HAS INDICATED HE WISHES
TO MAKE NO CHANGE IN MALE
MORTALITY RATES.
CHANGE IN MORTALITY OCCURING IN MALES
GROUPS (FROM AGEs TO AGE) ?45a '
REPORT: 71:
YEAR 1975 POP= 214.9 MILLION FERTILITY 2445
REPORT: ?3
YEAR 1989 POP= 227.2 MILLION FERTILITY 2645
PCT. TOTAL POP.
BeecccecesedSevscccceetiMeseccccelSeoenceve lt
~~ FS ® oe
i@ «+34 -« k
15.2.4 9.» .s
294 ~ OA «¢ - REPORT 3 PRESENTS THE AGE
25 - 89 . ke STRUCTURE OF THE POPULATION
30 = 34. < IN GRAPHICAL FORM.
35 + 39 * *
4A -«- 44 e 3
45 <- 49 o *
5G = 54 . *
95 = 59 -¢
64 - 64 ® *
65 - 69 ° *
16 «+ 74 ® *&
15+ « *
SAMPLE RUN #2 illustrates the use of selected year reports. By answer-
ing the first question with response "2", the student is able to skip reports
and investigate a longer period of time more quickly.
RUN #2 |
—- DO YOU WANT REPORTS 1) EVERY 5 YEAR INTERVAL
OR 2) SELECTED YEARS 22
YEAR AT START OF PROJECTION 271973
DO YOU ASSUME STANDARD FERTILITY C1=YESs9=N9) 22
FERTILITY IN 1970 2724
WILL FERTILITY €1) STAY AT 24 OR ¢€2) CHANGE SLOWLY
TO A NEW LEVEL 72 | |
WHAT FERTILITY WILL BE STABLE 22.96
HOW MANY DECADES UNTIL FERTILITY REACHES 2.96 23
DO YOU ASSUME STANDARD BIRTH DISTRIBUTION (1=YESs@=NO) 71
DO YOU ASSUME STANDARD SEX RATIO C1=YES,9=NO0) ?1
DO YOU ASSUME STANDARD MORTALITY ¢€1=YES,@=NO) 71
NO YOU ASSUME STANDARD POPULATION C1=YES,3=NO) 71
REPORT: 1)SHORT 2).LONG 3)GRAPH 4)CHANGE ASSUMPTIONS S)END 71
YFAR 1970 POP= 29468 MILLION FERTILITY 24
YEAR FOR NEXT REPORT 72494
REPORT: ?3
YEAR 23a POP= 264.2 MILLION FERTILITY 2246
PCT. TOTAL POP.
DevesvecceSevccvsed 1 Geescsuwe | Seecces e020
oe)
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a)
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eee es © © © © @ © © © we ©
*
75+ o :
YEAR FOR NEXT REPORT 72939
REPORT: ?5
ANOTHER PROJECTION (€1=YESs 9=NO) 22
V. KEY TO STUDENT LABORATORY INVESTIGATIONS
INVESTIGATION #1 WHAT EFFECT WILL CHANGES IN FERTILITY
HAVE ON POPULATION BY THE YEAR 2000?
This is a rather easy exercise. Intuitively, the student will hypothe-
size that increased fertility will increase the population in the year 2000.
To make this investigation more meaningful, ask your students (before they
start to calculate) their age in the year 2000 and the number of children
they want in their future families. (This last number equals fertility.)
While many students will be able to hypothesize the results, they may
be surprised at the large difference in population that would result if
fertility climbed back to its 1960 levels.
Additional Student Instructions
Students should pick at least four values for fertility (values between
2 and 4); all other factors should remain constant from projection to pro-
jection, To speed student use of the computer, encourage each student to:
1) use standard (1970) values for birth distribution, sex ratio,
mortality and population. These can be supplied by the com
puter program if the student responds to a question such as:
DO YOU ASSUME STANDARD SEX RATIO (1=YES, @=NO)?
by typing the number l.
2) select the short report on population. This is done by typing
the number 1 in response to:
REPORT ?
To make it possible for a large number of students to use the computer
in a very short time, USPOP allows the student to skip all the years between
1970 and 2000 before obtaining a report; this can be done by asking for reports
only on selected years. For smaller groups,it is suggested that vou encourage
students to get reports every 5 years. (See Sample Runs for illustrations.)
After running each projection, students should organize their resulting
data in a useful way, e.g., graphical techniques which give clear results.
The sample results following illustrate two possible graphing techniques.
POPULATION M nen
Sample Results
These results were obtained using the following fertilities (children/
women's completed family):
5 (control)
Nr WD
Your student's results will vary with the particular values he selects
to investigate.
SOLUTION TECHNIQUE #1 SOLUTION TECHNIQUE #2
POPULATION vs. TIME POPULATION IN YEAR 2000
FERTILITY
FERTILITY
340
& 320
&
<
= 300
Oo
x
5 280
a.
O
a
260
IS970 I980 I990 2000 2.0 3.0
YEAR FERTILITY
Both of these graphs indicate the clear effect that fertility has on
population growth. This is the reason that underdeveloped countries with
population problems attempt first to control fertility.
Sample Answers to Student Follow-up Questions - These are only sample
answers. Actual answers will vary with the fertilities that your stu-
dents have elected to study.
1) IF FERTILITY OF WOMEN IN THE UNITED STATES STAYS NEAR
THE 1970 LEVEL OF 2,45 CHILDREN PER FEMALE, HOW MANY
ADDITIONAL PEOPLE WILL THERE BE IN THE YEAR 2000?
Approximately /0 million people, assuming
that all other factors remain constant at
1970 levels.
2) WHEW YORK CITY HAS A POPULATION OF APPROXIMATELY
7 MILLION PEOPLE, HOW MANY NEW YORK-SIZED CITIES
WOULD HAVE TO BE BUILT TO ACCOMMODATE THIS INCREASED
POPULATION?
About 10 large cities would be required if
fertility remains at 1970 levels. A more
likely outcome might be a further increase
in the size of small and medium-sized com-
munities. This natural increase of the
population coupled with the flow to the city
of the rural population has caused great
concern on the part of urban planners.
3) IF FERTILITY WERE TO REMAIN LOW (FROM 2 TO 2,3), Na
WOULD THE PROBLEM OF EXTRA POPULATION BE AS
PRESSING? WHAT IN YOUR RESULTS INDICATES THIS?
If fertility were to fall to 2.3, we could
expect about 10 million fewer people in the
year -2000 than was projected above; this is
a drop of about 15%. Should fertility drop
still lower, even greater differences will
result.
4) IF FERTILITY WERE TO RISE TO LEVELS SEEN IN THE
MID-FIFTIES, APPROXIMATELY HOW MANY ADDITIONAL
PEOPLE COULD BE EXPECTED BY THE YEAR 2000 AS
COMPARED TO THE CURRENT U, S. POPULATION?
If fertility should return to about 3.7 children
per completed family, we would expect an increase
of 140 million people by the year 2000. This
represents an increase of approximately 652.
10
5) WHAT RELATIONSHIP EXISTS BETWEEN
FERTILITY AND POPULATION GROWTH?
Fertility has a direct effect on population
growth. The greater the fertility, the
greater the growth, and vice versa.
Additional Discussion Questions
¢ How many children does the average female student want
for her family? the average male?
* Will more or fewer women in the future raise families?
What will be the effect on fertility in either case?
* Has information on television and in print affected the
student attitude toward family size?
* What would happen if the fertility fell below 2.0?
(Use USPOP in class to solve this one. YOU AND YOUR
STUDENTS MAY BE SURPRISED.)
* How does USPOP help to plan for future ecology programs,
the energy crisis, and so forth?
11
tinea nemensnttaeienntiibleleaioalipeenditnersiinimememnnio—e
INVESTIGATION #2 WHAT EFFECT WOULD DELAYING THE BIRTH OF THE
FIRST CHILD HAVE ON POPULATION GROWTH?
We have found that most individuals feel that the time of birth should
have no effect on the rate of population growth. This is not the case.
While the effect is small at first, it is real, and over long periods of
time the delaying of births can have a significant effect.
It should be pointed out that the number of births to a female is
exactly the same in all the cases investigated in this experiment. If
a student should doubt this, have him investigate it for himself by ask-
ing for the long form of the printout.
Because the results are not intuitive and there are many possible
birth patterns, this investigation is more difficult than INVESTIGATION #13
but a student attempting to arrive at an original solution will almost
always produce gratifying results.
Additional Student Instructions
These are provided so you might help those students having trouble
setting up their investigation.
Only birth distribution should vary from run to run. If you have
your students use the EXPERIMENT PLAN SHEETS provided in the STUDENT
MANUAL, it should be easy to check whether all other variables are
being held constant. (It will be easiest for the student to set these
other variables to 1970 values.) |
Any birth distribution can be investigated. The only restriction
is that the numbers for all the fertile ages should sum to 100. (Numbers
Should be entered as percentages, not decimal fractions of 1.) Generally,
it is best for the student to select distributions that show a clear
effect: either few births in the early years or few births in the later
years. REMEMBER, one of the runs should use the current 1970 birth
distribution!
Runs will be quicker if students select report form 1, but all these
reports will give satisfactory data.
The STUDENT MANUAL suggests to the student that he graph the results
of each of his runs. You may instruct him as to the format. We feel that
putting all runs on a single graph with use of different colors will make
interpretation easier. (See sample results following. )
12
e ®
' Sample Results
Actual results will differ according to the sets of assumptions that
each student chooses to investigate, but the patterns should be similar.
Consider, for example, the following sets of assumptions:
TRIAL
AGES 1 2 3 4
10-14 efi) 33.2 .0 .0
15-19 0 (14.3) 33.4 = 2
20-24 n(33.8) 33.0 34 3
25-29 t (28.5) a 33.0 i
30-34 r (14.7) a 33.2 a
35-39 o( 6.6) = 33.4 33.0
40-44 1( 1.8) o2 2 33.4
45+ ¢. .0 ot 33.2
The resulting graph of POPULATION vs. TIME for each of these birth distribu-
tions is given below:
MOG TS? sobs: 2 “Ene y* SETH a
_ weeeeeeeeeees CURRENT BIRTH ‘
ia MIDDLE AGE 3 Ps
x — LATE BIRTHS oy
Z
=
a
=
=
z
fo)
>
ace
oa
oO
O
ae
I970 1980 1990 2000 2010 2020 2030
13
Sample Answers to Student Follow-up Questions
1) IF NO CHANGE OCCURRED IN BIRTH DISTRIBUTION, WHAT
WOULD BE THE EXPECTED POPULATION IN THE YEAR 2030?
Nearly 360 million people, assuming that all
variables remained near 1970 values.
2) DO YOU FEEL THAT LOWERING THE AGE AT WHICH MOST WOMEN
HAVE THEIR FIRST CHILD WOULD HAVE MUCH OF AN EFFECT ON
THE SIZE OF THE POPULATION? WHAT IN YOUR DATA SUPPORTS
YOUR VIEW?
Earlier births, especially in the teens, exert
a large force for growth in an expanding popu-
lation by an additional 40 million over what
would normally be expected in the year 2030,
if 1970 conditions were maintained.
3) WOULD IT BE WORTHWHILE FOR GROUPS INTERESTED IN
POPULATION LIMITATION TO ENCOURAGE WOMEN TO HAVE
CHILDREN AT A LATER AGE? WHY?
This is a matter of opinion. There are those
in family planning who maintain that the only
effective action is to reduce fertility; others
point to examples such as Ireland where later
births have been at least partially effective
in controlling the rate of growth.
4) COULD HAVING CHILDREN AT A YOUNGER AGE BE RELATED
TO ANY OF THE OTHER VARIABLES SUCH AS FERTILITY,
MORTALITY, SEX RATIO, ETC.?
In general, it would seem likely that having
children at a younger age would lead to in-
creased fertility. Also, since younger mothers
tend to have more boys than older mothers, this
might lead to a changed sex ratio. In India,
where many women become pregnant in their early
teens, there is some indication that early birth
is related to increased female and infant mortality.
The practice of having children at an older age
might lead to opposite effects.
14
5) IS THERE ANY GENERAL RULE THAT YOU CAN FORMULATE TO
RELATE BIRTH DISTRIBUTION AND POPULATION GROWTH? IS
THIS RULE SHOWN IN YOUR GRAPH?
For a growing population, the later the children
are produced in the mother's life, the lower the
rate of population growth.
As a follow-up in class, explore the effect of
all chiidren being born to a single age group.
Although this is an unrealistic assumption, it
will produce a clearer picture of the birth
distribution effect.
15
INVESTIGATION #38 WILL CHANGES IN INFANT MORTALITY
AFFECT FUTURE POPULATION LEVELS?
To carry out this investigation, the student must be able to vary infant
mortality. Since we view the population in 5-year age groupings (cohorts), the
student must adjust the interval 0 to 4 for both the males and the females.
This is a more complicated task than is required for either of the previous
investigations. If the student encounters trouble, consult the more detailed
operating instructions given below.
Our infant mortality rate, while a national disgrace, does not currently
depress the national population growth rate to any great extent. If altered
within the feasible range of change (see Sctentific American article, Aug. ‘71,
p. 45) slight changes might be detectable by the year 2020.
Should your students be concerned that they are not getting results, you
may wish to reassure them that not all experiments seem to show the antici-
pated result. No change 7s a result.
Additional Student Instructions
The student is asked to make from four to eight experimental runs using
different mortality rates. All other factors should remain the same from run
to run. If you have had the students make use of the EXPERIMENT PLAN SHEETS
found at the back of the STUDENT MANUAL, you should be able to detect improper
experimental design.
In order to vary the mortality for infants, the student must answer the
question "STANDARD MORTALITY?" with a "§$", representing NO. The computer pro-
gram will then ask what female age groups the student wants to vary. A proper
response would be "9,4" (from birth @ to age 4). The computer will give the
student the old mortality rate in deaths per 1000 and ask for a new rate.
Any number from % to 1000 can be typed. For this investigation it has been
suggested that the lowest possible mortality rate is near 17.5, but allow the
student to choose any rate he feels possible. After changing the female in-
fant mortality, the male mortality should be similarly adjusted.
Students may be encouraged to use Report Form 1 if speed is important,
but Report Form 2 (long report) is desirable for this exercise, since the
student can see the effect of infant mortality on those just born.
The STUDENT MANUAL indicates three possible ways in which the data might
be organized. It would be best to ask the students to try all three as a
homework assignment. (See Sample Results following for the two graphical
techniques.)
16
Sample Results
Each student's results will vary from those shown here depending on
the particular mortality changes the student elects to investigate. A
student may choose to investigate the following situations:
1) conditions of 1970 continuing
2) decreased infant mortality of 227
3) increased infant mortality of 207
Results of these runs were organized into two different graphical for-
mats. GRAPH 1 shows population size versus year; GRAPH 2 displays popula-
tion in the year 2020 versus per cent change in infant mortality.
3690 --- 22% DECREASE
— _ UNCHANGED
ns 20% INCREASE o
320 i
300 fe
280 “ae
IN MILLIONS
\
260 A
240 7 7
220
200
I970 I980 I990 2000 2010 2020
YEAR
POPULATION
\
GRAPH 1
17
POPULATION IN 2020 (MILLIONS)
The absolute effects
of 3 different infant
mortality rates on
population size are
small as indicated by
GRAPH 1; however,
changes in infant mor-
tality do affect popu-
332 lation size, if only
in a minor way, as
indicated in GRAPH 2.
33l
330
329
328
=20 -10 0 0D BW DD
% CHANGE INFANT MORTALITY
GRAPH 2
18
Sample Answers to Student Follow-up Questions
1) IF A DROP IN INFANT MORTALITY OCCURS, WILL IT
HAVE A MAJOR IMPACT ON FUTURE POPULATION LEVELS
IN THE UNITED STATES? WHAT DATA DO YOU HAVE TO
SUPPORT THIS CONCLUSION?
The impact of infant mortality changes
that are likely should prove to be very
small. GRAPH 1 indicates the effect.
2) IS THE EFFECT OF LOWERING INFANT MORTALITY MORE
IMPORTANT OR LESS IMPORTANT AS TIME GOES ON IN
AFFECTING TOTAL POPULATION SIZE?
As indicated by GRAPH 1, the difference
grows with time,
3) IT HAS BEEN SAID: "THOSE CHILDREN WHO MIGHT HAVE
DIED' DUE TO HIGH INFANT MORTALITY NOW LIVE LONG
ENOUGH TO HAVE CHILDREN OF THEIR OWN." DO YOU
FIND ANY PROOF FOR THIS STATEMENT? IF SO,
INDICATE WHAT IN YOUR RESULTS BACKS UP THIS
STATEMENT; IF NOT, INDICATE HOW YOUR DATA SHOWS
THIS IS NOT AN IMPORTANT FACTOR.
This is a matter of interpretation, If
the student has collected data using
Report Form 2 or 3, he may have a
positive indication. Have the class
look at such data and interpret it as
a group.
Additional Suggestion
We have restricted the students to investigating likely changes; but
unlikely changes are not impossible. Check the results of doubling infant
mortality, halving it, or even greater changes.
19
INVESTIGATION #4 HOW DOES FERTILITY AFFECT THE AGE
DISTRIBUTION OF THE POPULATION?
Up to this point the student has been investigating population growth.
We are now investigating something about the make-up of the population.
The size of the population in the next two investigations is relatively
unimportant.
Most demographers feel that the fertility rate of a population is
the prime determinant of age structure within a stable population.
Before starting the student on this investigation, discuss the age
structure of the United States population and possible reasons why there
are sO many more young people than old. (A graph of U. S. age distribu-
tion is shown in the STUDENT MANUAL under Investigation #4.) An alter-
native approach is to have your students canvass their area to determine
the age structure of the area.
Additional Student Instructions
These are included so that you might guide students who are unable to
resolve the problems involved in designing a meaningful experiment.
As fertility is the single variable that we wish to explore, it alone
should be varied from run to run; all other variables should remain fixed.
It will be easiest for the student if he maintains 1970 values for these
other variables.
For optimum results, the students should be encouraged to select a
wide range of fertilities, from 0.0 to at least 10. eport form 3 (or 2)
should be selected, since both these forms give results in terms of age
distribution.
The manner in which this data is organized is left up to each indi-
vidual. For those having trouble, these suggestions might prove useful:
1) Superimpose the graphs of age distribution for a
certain year (e.g., year 2030).
2) Approximate median age at a certain year for all
your runs and organize a table showing the relation-
ship of fertility and median age.*
3) Organize the graphs of age distribution for a certain
year, so that they are side by side for easy comparison.
*Median age can be approximated by cutting along both axes of the graph and
then along the line connecting the points. Hold the cut-out over a ruler
edge that is in the direction of the y-axis (i.e., Per Cent of Population
axis). Move the graph back and forth over the ruler until it is balanced.
The intercept of the ruler and the x-axis marks the approximate median age.
20
¢ *%
Sample Results
Your students’ results will vary with the particular fertilities that they
choose to work on. For example, let's assume that certain students chose to
investigate the following fertilities:
wie foe: 2
Tisai 2 6
T¥iai 3S = -2Z
Triai-4 “= —i
-45 (control)
Each trial was run to the year 2020. Run the trial for a longer period of
time if possible, since the longer the trial is run the clearer the results,
those born before the institution of the new fertility rate being eliminated
from the population.
Results of age distribution in the population were determined in two ways:
1) graph of population in the year 2020 versus age group, and 2) graph of median
age versus fertility.
O
>
w FERTILITY
oO
<_{ Be Fe © ereccccce 6
Y 15 — 245
z } ea
=
©
< lO a be.)
me
- ‘
a ae / \
Be = _- ~ PRE ee ~~
oO ae ion, =
5 a” ae ee ‘N
i si ig
= gi ne
Li] oes 0 ee
O ‘.
o
LiJ
ee 0 os
a tt Of $+ Qaem BT .oO mo tr Oo
Sa het Pe ees SFT
O “~ = w) Oo WwW \)
a N 3 ogee + YO WO 2 @ R oe
AGE GROUP
The above graph indicates a general pattern in a population with a high fertility:
the younger ages are dominant. In populations with low fertilities, there is
generally either an even distribution or an old-age dominant distribution.
21
MEDIAN AGE IN YEAR 2020
40
This graph shows the
relationship between
fertility and median
age. The higher the
fertility, the lower
the median age. In
other words, there is
generally an inverse
relationship between
fertility and median
age of a population.
| 2 3; °§ ro)
FERTILITY (1970-2020)
22
6
These are only examples of proper responses. Exact, correct responses
will be determined by the particular fertilities the student has chosen to
investigate,
1) FROM THE RESULTS OF YOUR EXPERIMENT, WHAT EFFECT
WOULD YOU SAY HIGH FERTILITY HAS ON THE AGE DIS-
TRIBUTION OF THE POPULATION?
High fertility causes the age distribution to show
a larger percentage of people in the younger age
classes.
2) IN COUNTRIES WITH LOW FERTILITY, WOULD YOU EXPECT
TO HAVE MORE OLD PEOPLE OR FEWER OLD PEOPLE OW A
PERCENTAGE BASTS? WHAT IN YOUR DATA SUPPORTS
YOUR OPINION?
With a lower fertility, the population should show
more old people. The data indicates that with low
fertility, the population tends to be more balanced,
whereas the United States with a high fertility
shows an age distribution that has many more young
people.
3) FROM YOUR RESULTS, ESTIMATE A FERTILITY THAT
WOULD RESULT IN AN EVEN AGE DISTRIBUTION
THROUGHOUT MOST OF THE POPULATION.
In general a fertility close to 2.0 will result in
a very even age distribution, if the fertility and
all other factors remain constant over a long
period of time.
4) GIVE A POSSIBLE REASON WHY THE 1970 U.S. AGE
| DISTRIBUTION SHOWS A DIP FOR THOSE AGES 30-39,
The age distribution graph, found in the STUDENT
MANUAL for Investigation #4, shows that the per-
centage of people of ages 30-39 is lower than
that of those immediately younger or older. It
is hoped that the students will realize that a
temporary drop in fertility 30 to 40 years ago
might have resulted in this drop. This period
roughly corresponds to the time of World War II
and the Great Depression. (For exact fertility
figures, see the RESOURCE MANUAL.)
23
INVESTIGATION #65 EFFECT OF MORTALITY ON AGE
STRUCTURE IN A POPULATION
Most students will feel that altering the mortality rates should affect
age distribution in the population as fertility did in the last investigation.
Surprisingly, mortality rates have only a secondary effect on the age dis-
tribution.
Students are to alter mortality rates for all age groups and view the
results. Realism is not required; in fact,the students should examine a
wide variety of changes, both increased and decreased mortalities.
Additional information on mortality trends can also be found in the
RESOURCE MANUAL and the STUDENT MANUAL.
Additional Student Instructions
The student must alter only mortality rates; all other variables should
remain the same from run to run. It is easiest if the other variables are
set to 1970 values.
Students should be encouraged to use a wide range of mortalities. The
larger the range investigated, the clearer the result. Mortalities should
be changed for all age groups (as opposed to only infants, as in Investiga-
tion #2). Reports should be obtained using either Form 2 (long report) or
Form 3 (graph of age distribution); either of these Forms will give the re-
quired information. If the student needs to work quickly, he may elect to
get reports for selected years only.
No direct instructions as to organization of data is given in the
STUDENT MANUAL. You may wish to instruct the students to organize their
data in a particular way. (See Sample Results for suggestion.)
Sample Results
Let's say a student chooses to investigate the following changes in
mortality:
Trial 1 -— doubled mortality for all ages
Trial 2 - 50% increase in mortality for all ages
Trial 3 - no change in mortality (1970 mortalities)
Trial 4 - 50% decrease in mortality for all ages
The results of all of these trials were compiled on a graph showing
the age distribution as percentages of the total population predicted for
the year 2020. Any other year might have been selected for analysis, but
the longer the time period, the clearer the results, generally.
24
PERCENT POPULATION IN 2020
MORTALITY (FOR ALL AGES)
—~— DOUBLED
e)
— 50% GREATER
CURRENT
- HALVED
-—~> bab
/f
a
>
~N
aN
O
o
+O eee es este shee & t
ew ee A ee gO
vu np ¢ $$ HO OG SF
AGE GROUP
Students should be able to conclude that while mortality has an effect
on the size of the population, it does not radically affect the age structure
of the population. The one exception is demonstrated in the oldest age
category, but this is not a real effect since any percentage change for the
oldest group represents a much larger absolute change in this group than in
any other group. (The students may wish to use a constant change in mortality
rather than a percentage change.)
Students should be encouraged to compare this result with the results of
Investigation #4, They should be able to conclude that fertility is usually
the prime determinant of age structure in a population.
25
Sample Answers to Student Follow-up Questions
1) IF THERE WERE A DRASTIC INCREASE IN MORTALITY
IN THE FUTURE CAUSED, SAY, BY MASSIVE AIR
POLLUTION, WOULD THE AGE DISTRIUUTION BE
AFFECTED? IF SO, IN WHAT WAY?
This question is open to interpretation. If the
student interprets the question as meaning there
will be a large increase in mortality for all
ages, then his response should mirror the results
of the experiment. However, if the student feels
that the very young or very old or both will be
particularly hard hit, then the student's response
may be somewhat different. In class, it is sug-
gested that you examine the student's assumptions
relative to this question and then use USPOP if
necessary to see if his conclusion is valid.
2) IF ALL AGES HAD A LOWER MORTALITY, WHICH AGE
GROUP WOULD SHOW THE GREATEST PERCENTAGE
INCREASE? HOW DO YOUR RESULTS INDICATE
THIS?
If all ages were to have identical decreases in ?
per cent mortality, then the older ages would \
benefit the most. This is indicated by Trial 4 \
of the Sample Results.
3) IF CURRENT MORTALITY CONDITIONS CONTINUED
FOR THE NEXT 50 YEARS, WOULD THE YOUNG
(LESS THAN 30) STILL DOMINATE THE
POPULATION?
The current median age in the United States is
less than 30. Should mortality and fertility
stay at 1970 levels, USPOP projects a median
age of about 37 in 2020. This indicates that
the dominance of the young would be waning,
but still strong.
4) IF ALL MORTALITY RATES WERE TO DECREASE
SUBSTANTIALLY, WHAT IMPACT WOULD THAT
HAVE ON THIS COUNTRY?
The question is open to discussion. Try to
channel discussion in such a way that the
students must support their conclusions with
their collected data.
26
VI. ADDITIONAL QUESTIONS FOR CLASS DISCUSSION
Should the United States make population limitation a major aim >
in future years?
If the United States determines that it is necessary to limit
future population growth, what factor(s) should be con-
sidered of prime importance?
In what ways has the United States adjusted its government and
life style to reflect the large number of young people in
the population?
What changes do you feel necessary for the future?
For additional ideas and investigations see the USPOP RESOURCE
MANUAL:
Readings
Class exercises
Further student investigations
27
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