(These instructions are an abridged and modified
version of the instruction manual: "DemoProj Version 4" by John Stover
and Sharon Kirmeyer)
You will need to collect data and make
certain decisions before running the model. The data you will need
include:
1. Starting the Spectrum Program
1. Click the "Start" button on the task bar.
2. Select "Programs" from the pop-up menu.
3. Select "Spectrum" from the program menu. Alternatively, you can use Windows Explorer to locate the directory "c:\spectrum" and double click on the file named "spectrum.exe".
2. Specifying the Projection Parameters in Projection Manager
To create a new projection:
1. Select "File" from the menu bar.
2. From the pull-down menu that appears, choose "New projection."
Next the "Projection manager" dialogue box will appear.
The following information is required to create a new projection:
Projection title: Enter the title you wish to assign to this projection. I suggest using your country names for this title which will be printed at the top of all printed output and will be used to identify the projection if more than one projection is loaded at a time.
Projection file name: You must also assign a file name to the projection. This is the name that will be used to store all data files associated with this projection. This name should not be more than eight characters in length and should not contain any illegal characters (you may use letters, numbers, and certain symbols such as a hyphen). Do not enter an extension with the file name; the program will automatically assign the extension ".pjn" to the projection file. If a box is shown in gray, you will not be able to change its contents. It means that another projection has been loaded, and the data must remain the same. If you want to create an entirely new projection, you should close the other projections, using "File" and "Close," and then select "File" and "New." Users may want to have several projections open in order to examine the effects of changing assumptions such as the final year total fertility rate.
1. Click on the "Projection file name" button to open an edit box and type the file name.
2. Click on "Ok" to accept or "Cancel" to reject.
First year: Click in the "First year" box to enter the first year of the projection: 2000.
Final year: Click in the "Final year" box to enter the final year of the projection: 2050.
Projection timeframe. The radio button (or option) labeled "Standard demographic projection < = 50 years" will be selected by default. This is the choice that you want.
Once all the information is entered for this dialogue box, click on the "Ok" button. You can always return to this screen and change some of the information by selecting "Edit" from the menu bar and "Projection" from the pull-down menu.
Active modules. These radio
buttons
(or options) let you select other Spectrum modules that will be used
with
the population projection. None need be selected.
1. Specifying New Demographic Projection
Parameters
For readers who feel they need additional review or explanations of the terms found in this section, the glossary at the end of these instructions may be useful.
To enter the assumptions for the population projection, select "Edit" from the menu bar and "Demography" from the pull-down menu.
Selecting the button labeled "Projection parameters" brings up a screen; in the top left part of this box the first year, final year and projection period are shown. These entries cannot be changed here; they are shown for information only. The other items in the dialogue box are as follows:
Currency Name: Type in the name to label the currency units. There is no need to change this option since we will not be using modules that estimate costs of policy interventions..
Urban/rural projection: There is no need to change the default setting since we will not be projecting urban/rural change in our projections.
Scale: Scale refers to the scale used when base year population figures are entered. The unit we will be using is "Thousands," which is the default setting.
Consider the case when the population in the base year is 10 million. If you select a scale of "Units," then you should enter the base year population as 10000000. If the you select a scale of "Thousands" then you should enter the base year population as 10000. If you select a scale of "Millions" then you should enter it as 10. For most country applications, "Thousands" will be the best choice. It will keep users from having to enter very long numbers while still leaving enough digits for adequate precision.
Click on the "Ok" button to close the
dialogue
box.
2. Entering the Base Year Data and Projection Assumptions
To enter the base year data and projection assumptions:
1. Choose "Edit" from the menu bar.
2. Choose "Demography" from the pull-down menu.
3. Choose "Demographic data" from the "Demographic data" dialogue box. This step will display an editor.
For each of the inputs required for the population projection, there is a tab near the top of the screen.
1. To enter data for any of these assumptions, click on the appropriate tab to display the editor for that variable.
2. Then click anywhere inside the editor to make it active. To enter data for any of these assumptions, click on the appropriate tab to display the editor for that variable. Then click anywhere inside the editor to make it active.
Although you can enter the data in any
order,
it is generally best to begin by entering the data on the first
year
population as this information is needed to calculate some of
the
indicators displayed in the "ASFR" and "Model life table" editors. Each
of the editors is explained in the following pages.
3. About the Editors
Each editor in DemProj is similar. At the very top of the screen, the variable name appears. At the bottom of the screen are the special edit keys. "Duplicate" allows you to copy information from one cell, column or row to another; "Interpolate" to enter a beginning and ending number and have the computer calculate numbers for the intervening intervals; "Multiply" to multiply a cell, column or row by a specific number; and "Source" to write notes indicating the source of the data for future reference.
To use the "Duplicate" button,
1. Highlight (select) the range (column, row, or cells to be affected). The first cell in the range should be the value you want to copy.
2. Extend the range to the last year by using the mouse (hold down the left button and drag the range) or the keyboard (hold down the shift key and use the arrow keys).
3. Click on the "Duplicate" key to copy the value at the beginning of the range to all the other cells in the range.
To use the "Interpolate" button,
1. Enter the beginning and ending values in the appropriate cells.
2. Highlight the entire range from beginning to end.
3. Click on the "Interpolate" key to have the values interpolated and entered into each of the empty cells.
To use the "Multiply" button,
1. Highlight the range (column, row, or cells to be affected).
2. Enter the multiplier in the dialogue box.
3. Click "Ok" to accept. The entire range will be multiplied by the designated number.
To use the "Source" button,
1. Click on the "Source" button to open a small word processor window.
2. Enter the source of the data and make any special comments about the assumptions.
3. Click on "Close" to return to the editor.
This feature allows you to keep a record of the data sources and assumptions as you make the projections. This source information will be maintained with the data file and printed whenever you print the projection summary. It is strongly recommended that you use this feature to avoid later confusion.
When you have finished entering all the necessary data for the component into the editor,
1. Click the "Ok" button to return to the "Sector selection" dialogue box.
2. Click the "Close" button to complete the editing process, or
3. Click on another sector to edit the data for that sector.
The "Cancel" button allows you to exit the editor without making any changes to the data for the sector.
First Year Population
DemProj does have range limits built into the individual editors. For example, the model will accept estimates of life expectancy between 32.5 and 87.5. If you enter a value such as 125, you will be prompted to change the number.
The population by age and sex in the base year is entered in this editor. The scale is shown at the top of the editor. In our example, the scale we chose was "Thousands." Thus, a figure such as 43,230 would be entered as 43.23. Since DemoGraphic 96 data on your printed "age-sex" table is already in "000s" you simply have to directly type in the data from this table --
1. Enter the size of the population by
age
and sex in the appropriate cells of the editor. The total number of
males
and females will be automatically calculated and displayed in the last
row of each column. After entering all your numbers, check the total to
see that it is within one or two of the total on you DemoGrahics 96
table.
Once all the data are entered correctly, click on the tab "Total fertility rate" to move to this editor.
Total Fertility Rate
This editor is used to enter the base year total fertility rates (TFRs) and the assumed future TFRs. The first few years will be shown on the screen. To use this editor,
1. Click somewhere inside the editor to make the scroll bar appear.
2. Scroll to the right or left to see all the years.
3. Enter a TFR for every year of the projection.
For an initial trial projection, keep the TFR constant at the year 1995-2000 value that is found on your DemoGraphics 96 "vital rates" table. You can enter the base year value and then use the "Duplicate" key; duplication may be done for any interval of time. To duplicate a value:
1. Highlight (select) the range. The first cell in the range should be the value you want to copy. Extend the range to the last year using the mouse (hold down the left button and drag the range to the right) or the keyboard (hold down the shift key and use the right arrow key to scroll to the right).
2. Then click on the "Duplicate" key. This step will copy the value at the beginning of the range to all the other cells in that range.
When you do your actual population projection for your country, you will need to make an educated guess about what the TFR will be in each of your countries over the next fifty years. If you have completed project Tables 7-1 and 8-1 then use the TFR figures from those tables. If not, begin by sitting down and thinking about fertility trends in your two countries. Examine the fertility section of your project, focusing on recent trends in the total fertility rate. Also think about what has been happening to contraceptive use over time. Make an educated guess as to what you think will happen to the total fertility rate in each of your countries over the next 50 years. You may want to enter a TFR value for the first year and the last year and interpolate between these values to fill in the intervening years; interpolation may be done for any interval of time. To do this,
1. Enter the TFR values in the first and last years.
2. Highlight (select) the entire range from the first to the last year.
3. Press the "Interpolate" key. Values will be interpolated and entered for each of the years between the first and last.
For example, you may think that the TRF will fall from 5.2 in the year 2000 to 3.2 in the year 2020 and then fall more gradually from 3.2 in 2020 to 2.4 by the year 2050. You would simply do two interpolation procedures described above to input annual TFR data for the entire projection period of 2000 to 2050. If you have changed your TFRs every 5 years or 10 years, then you simple interpolate between the 5 or 10 year entries. When you have entered the information on the TFR, click the "ASFR" tab to move to the next editor.
ASFR
This editor is used to set the distribution of fertility by age.
There are three ways to specify the age distribution of fertility. You can use the United Nations fertility model tables, enter your own distribution, or use the Coale-Trussell fertility model (see the glossary or Chapter III for more about these distributions).
United Nations Model Tables. The default is to use the United Nations model tables. This is option that we will use. Select a particular UN table by clicking on the button next to the name of the table you want to use. To the right of each table name you can see the crude birth rate that would be calculated for the base year if you selected that table. Check what the CBR is on your DemoGraphics 96 "Vital Rates" table for 1995-00. Choose the UN Table that has the CBR that comes closest to this CBR. (This column will show CBR = 0.0 for all tables if you have not yet entered the base year population or TFR, so do this option only after having enter the age-sex and TFR info). Data for the age distribution of fertility will be calculated from the TFR and the selected model table only when you leave the "Demographic data" editor.
Sex Ratio at Birth
The editor for sex ratio at birth (see sample screen below) requires only a single piece of information: the number of male births per every 100 female births. This figure is set by default to 105. For most countries it will be about 103 to 105. The CIA Factbook contains an estimate of the sex ratio at birth for each country. You should check this source to see if the default value is appropriate for your country -- you should do these especially if you have an East or Southern Asian country in which couples might be aborting female fetuses in significant amounts. You may enter a new number in the edit cell or accept the default value; a message (warning) box will appear if an invalid number such as 300 is entered.
Once you have specified the birth ratio, click on the "Life expectancy" tab to move to this editor.
Life Expectancy
The life expectancy editor (see sample screen below) is used to enter the life expectancy at birth for both males and females in the base year, and to enter assumed values for future years. The first few years will be shown on the screen.
1. Click somewhere inside the editor to make the scroll bar appear.
2. Scroll to the right or left to see all the years.
3. Enter life expectancy for every year of your projection. The model will accept estimates of life expectancy between 32.5 and 87.5. If you enter a value such as 125, you will be prompted to change the number.
For an initial trial projection, keep the male and female life expectancies constant at the year 1995-2000 values that are found on your DemoGraphics 96 "vital rates" table. You can enter the base year value and then use the "Duplicate" key. To copy a value,
1. Highlight (select) the range. The first cell in the range should be the value you want to copy. Extend the range to the last year using the mouse (hold down the left button and drag the range to the right) or the keyboard (hold down the shift key and use the right arrow key to scroll to the right).
2. Then click on the "Duplicate" key. This step will copy the value at the beginning of the range to all the other cells in that range.
When you do your actual population projection for your country, you will need to make an educated guess about what the male and female life expectancies will be in each of your countries over the next fifty years. If you have completed project Tables 7-1 and 8-1 then use the life expectancy figures from those tables. If not, begin by sitting down and thinking about mortality trends in your two countries. Examine the mortality section of your project, focusing on recent trends in life expectancy. Also think about what has been happening to rates of HIV infection recently. Make an educated guess as to what you think will happen to the life expectancy values in each of your countries over the next 50 years. You may want to enter a life expectancy value for the first year and the last year and interpolate between these values to fill in the intervening years. To do this,
1. Enter the life expectancy values in the first and last years.
2. Highlight (select) the entire range from the first to the last year.
3. Press the "Interpolate" key. Values will be interpolated and entered for each of the years between the first and last.
When doing your actual projections you can interpolate between any number of years. For example, you can project a decrease in life expectancy from 2000 to 2015 if you think that AIDS will spread in your country, and than project an increase in life expectancy for 2015 to 2050.
When you have entered the information on the life expectancy, click the "Model life table" tab to move to this editor.
Model Life Table
Once you click the "Model life table" tab, you should see a dialogue box.
With this dialogue box you can specify which model life table (see glossary) should be used for this projection. Values for both the four Coale-Demeny model life table families and five United Nations model families are shown. The display also shows the crude death rate and the infant mortality rate that would be calculated in the first year if you chose the corresponding life table. Check what the crude death rate and the infant morality rate are on your DemoGraphics 96 "Vital Rates" table for 1995-00. Choose the UN Table that has the CDR and infant mortality rate that comes closest to your DemoGraphics 96 rates. Choose the appropriate table by clicking on the name of the table. The age-specific mortality rates needed by the program will be calculated based on the life expectancy and model life table when you leave the editor.
Once you have chosen the model life table, click on the "International migration" tab to move to the next editor. If you do not wish to consider international migration in this projection, you may skip this editor. Review the migration section of your project to determine is there is significant net "in" or "out" migration in each of your countries.
International Migration
International migration is specified through three input screens. When you select the "International migration" tab you will see the editor.
In this editor you specify the number of net male and female migrants. If the direction of the net migration is out of the country, then the figures should be negative; if the direction of the net migration is into the country, then the figures should be positive. Enter figures for male and female migration for all years. Remember, you are working in '000s so that a -5 in the male column means a net out migration of 5000 males in that year. If you leave the figures set to zero there will be no effect of international migration in the projection. If you have completed project Tables 7-1 and 8-1 then use the net migration figures from those tables.
Once you have specified the net number of migrants, you can specify the age distribution of these migrants. Click on the "Male age distribution" button to enter the age distribution for male migrants and the "Female age distribution" button to enter the distribution for female migrants.
4. Leaving the Demographic Data Editors
Once you have entered all the necessary information,
1. Leave the demography editors by clicking on the "Ok" button in any of the editors. When you click the "Ok" button, the program will record your changes and return to the "Demographic data" dialogue box.
2. Click on "Close" to keep your work, and you will return to the main program. If you decide that you do not want to keep the changes you have just made, click the "Cancel" button in any editor. This will exit the demography editors and restore all inputs to their values before you entered the demography editor. Any changes you made during the current editing session will be lost.
5. Saving the Input Data
Once you have entered the projection
assumptions,
it is a good idea to save the data onto your floppy disk. To do this,
select
"File" from the menu bar and "Save projection As" from the pull-down
menu.
Change the "Drives" option to "a:" , insert your floppy disk and hit
"OK."
The data will be saved using the file name you specified earlier.
Whenever you enter data for a new
projection
or edit the assumptions, DemProj will note that the data have been
changed.
The next time you try to display an indicator it will inform you that
the
data may have changed and ask if you want to recalculate the
projection.
Normally, you should answer "Yes" to this question. DemProj will then
make
the population projection. Once the projection is made, you will not be
asked again if you want to project the population, unless you edit the
assumptions.
To see the results of the projection,
select "Display" from the menu bar. From the pull-down menu select
"Demography."
You will then see another menu showing the seven categories of
indicators
available:
Choose one of these categories and you
will see one final menu listing the indicators available in that
category.
Select one of the indicators. Then you will see the display dialogue
box.
The exact choices available will depend on the indicator you have selected. For "Total population" you can set the region to "Total," "Urban," or "Rural" if you are doing a regional projection. The sex can be set to "Both," "Male," or "Female." The display interval will normally be in single years but you can change it to display every five or ten years if desired. The chart type is also set through this dialogue box. Click on the button next to the type of display you want. Normally the display will show all the years in the projection. However, if you want to see only part of the projection, you can change the final year by selecting a new final display year from the "Final year" list box.
Once you are satisfied with the type of display, click the "Ok" button and the display will appear.
All the projections that are currently in use will be displayed on the same graph.
You can change the configuration of the display by clicking the "Configure" button. You can also change the type of display by putting the mouse pointer anywhere inside the chart and clicking with the right mouse button.
To close the display, click on the
"Close"
button. You do not have to close the display immediately. You can
choose
to display another indicator and it will appear on top of the first
display.
The first display will be covered but it will still be there. You can
return
to any previous display that you have not closed by choosing "Window"
from
the menu bar and selecting the name of the display from the pull-down
menu.
From the "Window" selection you can also choose to tile or cascade all
the existing display windows.
1. Graphs and Bar Charts
Spectrum will display a variety of
graphs
and bar charts, including:
2. Tables
Spectrum will also display data in the form of tables. In tables, each projection that is in use will be displayed in a separate column. You can scroll through the table to see all the years using the PgUp and PgDn keys or the mouse.
To print a table, select "File" from the
menu bar and "Print" from the pull-down menu.
3. Displaying All Age Groups
If you wish to see the population size by age and sex, choose "Display," "Demography," "Age groups," and then "All age groups."
You can display the information as a table or as a population pyramid (see glossary) showing either numbers of people ("Pyramid (numbers)") or the percent distribution by age and sex ("Pyramid (percent)").
The pyramid display always shows two pyramids. If you are using a single projection, then the pyramid on the left will always be for the base year. You can change the year for the pyramid on the right by clicking one of the buttons at the bottom of the screen to advance the pyramid one year ("Next"), show the previous year ("Previous"), show the first year ("First year") or show the last year ("Last year").
If you have two projections loaded, then the pyramid on the left will display the first projection and the one on the right will show the second projection. Both pyramids will display the same year; using the "Next" and "Previous" buttons will change both pyramids.
If you have more than two projections
loaded,
you will be asked to choose which two pyramids should be shown before
the
pyramids appear.
4. Demographic Summary Table
The final display available in DemProj
is
a summary table showing all the demographic indicators. You can scroll
through this page to see all the output. If you have more than one
projection
loaded, the indicators for the second projection will immediately
follow
the first. To print a table, select "File" from the menu bar and
"Print"
from the pull-down menu.
5. The Specific Summary Table, Graphs and Age-Sex Pyramids Needed for the Project.
Using the "Spectrum" program, generate the following tables and graphs for each country.
Table:
Age-sex pyramid (number), first year (2000) & last year (2050):
It is always a good idea to save the
projection to your hard drive whenever you make a change to any
assumptions.
To save the projection without changing the name, choose "File" from
the
menu bar and "Save projection" from the pull-down menu.
To save the projection with a different
name, choose "File" from the menu bar and "Save projection as" from the
pull-down menu. You will then have a chance to specify a new file name
for the projection. Normally when you save the projection with a new
name,
you should also change the projection title. This will avoid confusion
if you have both projections loaded at the same time.
If you have already created a DemProj
projection or are using a projection provided by someone else, you can
immediately load that projection.
1. Select "File" from the menu bar.
2. Select "Open projection" from the pull-down menu. Insert your floppy disk and choose "a:" from the "Drives" option.
3. Select the file you wish to use and click the "Ok" button to open the projection.
You can open more than one projection at a time. Just repeat these steps to load a second or third projection. When you have more than one projection loaded, all projections will be displayed in the graphs and tables. The number of projections you can load at any one time is determined by the amount of available memory in your computer.
When you have more than one projection
loaded,
you will be asked to choose a projection when performing certain tasks,
such as editing assumptions. The program will display a list of the
projection
names and you may choose the appropriate one from the list.
To close a projection that has already
been opened,
1. Choose "File" from the menu bar, and
2. "Close projection" from the pull-down menu. If you have more than one projection loaded, you will be asked to select which projection should be closed.
3. Closing a projection just removes it from the computer's memory; it does not erase it from your disk. You can open that projection again at any time.
Many of the following terms were obtained
from the Population Reference Bureau's Population Handbook (1989);
others were adapted from the International Union for Scientific Study
of
Population's (IUSSP's)
Multilingual Demographic Dictionary (Van
de Walle and Henry, 1982).
Age-specific fertility rate (ASFR). The number of births in a year for a population of a given age and sex to the mid-year population of that same sex and age group.
Annual growth rate (GR). The rate at which the population is increasing or decreasing in a given year due to natural increase and net migration, expressed as a percentage of the base population.
ASCII (text) file. A file of text or data in a standardized, character format, which is transportable between software applications and operating systems.
Births. The total number of annual births.
Child-woman ratio. The number of children under the age of five per woman of childbearing age (15-49).
Coale-Demeny model life tables. Families of life tables derived from empirical life tables of Europe and other industrialized nations of the world. They are based primarily on data from the first half of the 20th century.
Coale-Trussell relational fertility model. This model incorporates (1) the timing of marriage, (2) a population's natural fertility, and (3) the degree of fertility regulation in a population. It permits users to generate a fertility schedule from an empirical baseline and a specific total fertility rate.
Cohort. A group of persons who experience certain events within a specified period of time, such as those who are born or who are married in the same year.
Cohort component projection. A projection made by subjecting all cohorts, on an annual or five-year basis, to mortality and migration assumptions, and applying fertility assumptions to women of reproductive age.
Crude birth rate (CBR). The number of live births per 1,000 population in a given year.
Crude death rate (CDR). The number of deaths per 1,000 population in a given year.
Deaths. The total number of annual deaths.
Dependency ratio. The ratio of the economically dependent part of the population (those aged 0-14 and 65 and over) to the productive part (those aged 15-64).
Dialogue box. A box permitting users to choose among a limited number of options. The box is accompanied by text elaborating upon those options.
Doubling time. The number of years it would take for the population to double its current size at the current annual rate of growth.
Fifth root. The fifth root of the number "n" is the number which, multiplied by itself five times, exactly equals "n." For example, the fifth root of 243 is 3 (3x3x3x3x3).
Gross migration. The total number of people who move to and depart from an area.
Gross reproduction rate (GRR). The average number of daughters that would be born to a woman (or a group of women) during her lifetime if she passed through all her childbearing years conforming to the age-specific fertility rates of a given year. This is similar to the TFR except that it counts only daughters.
Infant mortality rate (IMR). The number of deaths to infants under one year of age per 1,000 live births.
Initial age distribution. The age-sex distribution at the beginning of a projection period.
Interpolation. Given two numbers that serve as boundary points, it is possible to estimate the values that lie at intervals between the two points. For example, if the total fertility rate for a country or region was actually measured only in 1980 and in 1995, by assuming even increments from year to year, it is possible to interpolate a TFR for each intervening year. (Spectrum uses a linear form of interpolation so that the difference between each annual value is the same. Other nonlinear forms of interpolation also are possible, but are not used in Spectrum.)
Life expectancy (e(0)). The average number of years a newborn can expect to live based on the mortality conditions at the time.
Life table. A table of values based on a series of related functions having to do with survivorship over intervals of time.
Logit. A function of the real number x (where x must be between 0 and 1), which is defined as logit(x) = ln(x/(1-x)).
Mean age of childbearing. The average age of mothers at the time of birth.
Median age. The age that divides a population into two numerically equal groups.
Model life table. A table of values based on a series of related functions having to do with survivorship over intervals of time.
Net migration. The number of people who move to an area minus those who move away.
Net reproduction rate (NRR). The average number of daughters that would be born to a woman (or a group of women) during her lifetime if she passed through all her childbearing years conforming to the age-specific fertility rates and age-specific mortality rates of a given year. This is similar to the GRR except that it includes the effect of mortality that would cause some women to die before completing their childbearing years.
Normalized. The transformation of a series of data points to a percent distribution summing to 100 percent.
Population aged 0-4. The portion of the population under age five. It is often of interest as it may be subject to high mortality, and consequently may require a large amount of health care relative to other age groups.
Population aged 5-14. The portion of the population which is generally considered to be of school age.
Population aged 15-64. The portion of the population which is generally considered to be of employment age.
Population aged 65+. The portion of the population which is generally considered to be of post-employment age.
Population projection. Computations depicting the future course of a population's size, its structure, and its interaction with dynamics such as fertility, mortality, and migration. The projection is constructed based on assumptions about the future course of those population dynamics.
Population pyramid. A graphic that portrays an age-sex distribution. It is so named because of its shape.
Pop-up menu. A menu from which users can select items or actions. Pop-up menus can appear anywhere on the screen.
Probability of dying (qx). The probability that an individual (or group of individuals) having lived to exact age x will die before reaching exact age x+5.
Probability of survival (sx). This term is the complement to the probability of dying. It refers to the probability that an individual who has reached exact age x will go on to live to exact age x+5.
Pull-down menu. A menu opened by clicking on key words at the top edge of the screen. Pull-down menus allow users to select operations.
Quinquinnial. Five-year age groups. The basis for most cohort component projections is five-year age groups over five-year intervals.
Radio button. These buttons emulate raised buttons on early radios, which were punched to select radio stations. The graphically portrayed raised "radio buttons" on interfaces permit users to select among at least three alternatives.
Rate of natural increase (RNI). The rate at which the population is increasing or decreasing in a given year due to the surplus or deficit of births over deaths, expressed as a percentage of the base population.
Semi-log graph. A graph of data points for which one axis is graduated logarithmically, and the other is not, almost always being arithmetic instead.
Sex ratio. The number of males per 100 females in a population.
Survival ratio. The proportion of the population of a particular age that survives to the next age in the next year.
Synthetic (hypothetical) cohort. A cross-section of the population whose various demographic experiences (such as mortality chances) are consolidated into summary indicators, as if to a true (birth) cohort.
Total fertility rate (TFR). The average number of children that would be born alive to a woman (or a group of women) during her lifetime if she were to pass through all her childbearing years conforming to the age-specific fertility rates of a given year.
Under five mortality rate (U5MR). The number of deaths to children under the age of five per 1,000 live births.
United Nations model fertility schedules. Five regional schedules prescribed by total fertility rate.
United Nations model life tables for developing countries. A set of families of life table schedules derived from empirical life tables from developing countries, based on data from the second half of the 20th century.
Vital statistics. Statistics on demographic events--births, deaths, marriages, and divorces--which are recorded through an event registration system.