24 3.1.6 Net Reproduction Rate (NRR) It is the average number of daughters that would be born to a woman (or a group of women) if she passed through her lifetime from birth conforming to the age-specific fertility and mortality rates of a given year. This rate is like GRR but is always lower because it takes into account the fact that some women will die before completing their childbearing years.
o x x l l f NRR / 2 / 1 + ∑
Where,
= xf Fertility rate at age x specific for sex
= + o x l l / 2 / 1 Probability of surviving from birth to age x + ½
= ∑ Over all ages in the reproductive life span
3.1.7 Replacement - Level Fertility It is the level at which women in the same cohort have exactly enough daughters (on average) to “replace” themselves in the population. A Net Reproduction Rate (NRR) of 1.00 is equal to replacement level.
3.1.8 Nuptiality It refers to marriage as a population phenomenon, including the rate at which it occurs, the characteristics of persons in marriage, and the dissolution of such unions through divorce, separation, widowhood, and annulment.
3.1.9 Fecundity It is a physiological ability of a woman to conceive.
3.1.10 Sterility It is the inability of a woman to conceive. It can either be primary or secondary.
3.2 Mortality Mortality refers to deaths that occur within a population. The probability of dying during a given time period is linked to many factors, such as age, sex, race, occupation and social class. The incidence of death can reveal much about a population's standard of living and health care. It is measured using some of the following indicators:
25 3.2.1 Crude Death Rate (CDR) or Death Rate It is the number of deaths in a calendar year per 1,000 Mid-year population in a given year.
( ) 000 ,1 Pr × −
population ojected population year Mid year calender a in deaths of Number CDR
3.2.2 Age-Specific Death Rate (ASDR)
It is the number of deaths among the population in a specific age group per 1,000 of
that specific age group in a given year.
For example:
000 ,1 ) 24 20 ( 24 20 ) 24 20 ( × − − −
− years of population year Mid years population the among deaths of Number ASDR
3.2.3 Cause-Specific Death Rate (CSDR) It is the number of deaths due to a specific cause during a given year per 100,000 populations. For example: 000 , 100 1 ) ( × −
population year Mid year in cancer from deaths of Number Cancer CSDR
The cause-specific death rates are usually expressed in deaths per 100,000 because for most causes of deaths, rates of occurrence are very low.
3.2.4 Neonatal Mortality Rate (NMR) It is the number of deaths to infants under 28 days of age in a given year per 1,000 live births in that year.
000 ,1 28 inf ×
year that in births live of number Total year given a in days under ants to Deaths NMR
3.2.5 Infant Mortality Rate (IMR) It is the number of deaths of infants under the age of 1 year per 1,000 live births in a given year.
Z[9 = @ABCDE GHSDQLℎN LG JPH Q PLN APSDE 1 \DQE ]GLQI PABCDE GH IJKD CJELℎN JP LℎQL \DQE ×1,000
26 3.2.6 Post Neonatal Mortality Rate (PNMR) It is the number of infant deaths aged between exactly 4 weeks (28 days) and under 1 year of age per 1,000 live births in a given year.
000 ,1 ) sin ( 1 4 ×
year that birth Total births live year under and weeks exactly between aged deaths Infant PNMR
3.2.7 Child Mortality Rate (CMR) It is the number of deaths of children aged 1 year and above but below 5 years of age per 1,000 live births in a given year.
000 ,1 5 1 ×
year that in births live of number Total years below but year aged deaths of Number CMR
3.2.8 Under 5 Mortality Rate (U5MR) It is the number of deaths of children below 5 years of age per 1,000 live births in a given year.
000 ,1 1 5 0 5 ×
year that in births live of number Total year in and age between deaths of Number MR U
3.2.9 Maternal Mortality Rate (MMR) This is the number of women who die from any cause related to or aggravated by pregnancy or its management during pregnancy and childbirth or within 42 days of termination of pregnancy, irrespective of the duration and site of the pregnancy, per 100,000 live births.
000 , 100 ×
year that in births live of number Total year given a in deaths maternal of Number MMR
3.2.10 Life Expectancy It is an estimate of the average number of additional years a person could expect to live if the age-specific death rates for a given year prevailed for the rest of his or her life.
27 3.2.11 Life Expectancy at Birth It is an estimate of the average number of years a new born baby would live subject to the mortality risks prevailing for the cross –section of the population at the time of its birth.
3.3 Migration It is the geographic movement of people across a specified boundary for the purpose of establishing a new permanent or semi-permanent residence. The terms "immigration" and "emigration" are used to refer to movements between countries that is international migration. Corresponding terms to immigration and emigration for movement between areas within a country, that is internal migration are; in-migration and out-migration respectively.
3.3.1 Immigration Rate It is the number of immigrants arriving at a destination per 1,000 persons at that destination in a given year. Immigration Rate = Number of Persons entering an area immigrants Total population in that area × 1, 000
3.3.2 Emigration Rate It is the number of emigrants going away from an area of origin per 1,000 of the population at that area in a given year.
000 ,1 ×
area that in population Total area an from departing persons of Number Rate Emigration
3.3.3 Net Migration It is the net effect of immigration and emigration on an area's population. It may be an increase, a decrease or zero.
3.3.4 Net Migration Rate (NMR) It is the "net migration" of an area per 1,000 of the population of that area in a given year.
000 ,1 × −
area that in Population Total Emigrants of Number immigrants of Number NMR
28 3.4 Population Change Population change has three components: births, deaths and migration. As people are born, die or move, their total number in an area do change.
3.4.1 Natural Increase (NI) It is the surplus (or deficit) of births over deaths in a population in a given time period. D B NI −
Where,
NI is the natural increase during a period
B is the number of births and
D is the number of deaths during that period.
3.4.2 Rate of Natural Increase (RNI)
It is the increase or decrease of the population in a given year due to surplus (or deficit)
of births over deaths, expressed as a percentage of the base population. The RNI does
not take into account the effects of immigration and emigration.
For example;
100
×
−
year at it Population Total Year in Deaths Year in Births Year RNI
The rate of natural increase can also be calculated from birth and death rates as;
10 Rate Deaths Rate Births RNI −
3.4.3 The Balancing Equation It is the basic method of calculating numerical population change over time. The following is the equation;
( ) ( ) E I D B P Pt − + − +
0
Where,
Pt = Population at a later date/ Pop at time t
Po = Population at an earlier date/ base year pop
B = Births between the two dates
D = Deaths between the two dates
I = Immigrants between the two dates
E = Emigrants between the two dates
29
3.5
Population Growth
Refers to the change in population over time, and can be quantified as the change in the
number of individuals in a population using "per unit time" for measurement.
3.5.1 Population Growth Rate (GR) It is the rate at which a population is increasing (or decreasing) in a given year due to natural increase and net migration, expressed as a percentage of the base population. The growth rate takes into account all components of population growth: births, deaths, and migration. For example;
3.5.2 Inter-Censual Growth Rate It is the rate at which a population increases (or decreases) between two population censuses. This is obtained from the following formula; rt o t e P P =
Where; tP = Population at time t oP = Base year population e = Exponential r = Growth rate t = Time
Growth rate r is derived as follows rt t e P P
⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ 0
( ) rt e P P rt t
= ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ln ln 0
t P P r o t ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛
ln
GR;<;; = (Births in 2022 −Deaths in 2022) + Net migration in 2022 Total Population in 2022
30 3.5.3 Population Doubling Time This is a time a population would take to double its size at its current growth rate. A quick way to approximate doubling time is to divide 70 by the growth rate expressed as a percent.
tu] = v< wxyz{| x}{~ (%)
3.6
Population and Housing Census (PHC)
This is the total process of collecting, compiling, evaluating, analyzing and publishing or
otherwise disseminating demographic, economic and social data pertaining, at a specified time,
to all persons in a country or in a well delineated part of a country.
3.6.1 Census Night Is the reference night before the day that the actual counting begins.
3.6.2 De facto Methodology
De facto census is the method of enumerating individuals as of where they are found
during the census night, regardless of where they normally reside.
3.6.3 3.6.1 De Jure Methodology De Jure census is the method of enumerating individuals according to their regular and legal residence.
3.6.4 Enumeration Area (EA) Enumeration Area (EA) can be defined as the smallest spatial unit usually used by an enumerator during census enumeration. Usually EA have an average of 60 to 100 households
3.6.5 Optical Mark Reader (OMR)
Is the process of capturing data by optical scanner by measuring the reflectivity of light
at pre-determined positions on a surface.
3.6.6 Post Enumeration Survey (PES) Is the sample survey conducted within few months after the census for the primary purpose of evaluating the census. It helps in identifying areas of deficiencies that need improvement in subsequent censuses.
3.6.7 Population Density Refers to number of people living in a given area per square kilometer of land.
31
3.6.8 Population Share Refers to the percentage of population of a certain area for example region and district to that of total population of country, or region respectively.
3.7 Age Age is the number of years one had lived as of his/her last birthday
3.7.1 Median Age
Is the age at which exactly half of the population is older and the other half is younger
3.7.2 Myers’ Index
Is calculated for the age above 10 years and shows the excess or deficit of people in
ages in any of the ten digits (digits “0” to “9”) expressed as percentage. It is based on
the assumption that; the population is equally distributed among all ages. The
theoretical range of Myers` Index is from 0 to 90, where “0” indicates no preference,
while “90” indicates absolute preference.
3.7.3 Population Pyramid
Is a graphical presentation of population’s age and sex composition. Horizontal bars
present the numbers or percentages of males and females in each age group.
3.7.4 Sex Ratio
Is the ratio of males to females in a given population usually expressed as the number
of males for every 100 females.
3.7.5 Sex Ratio Under One Year of Age
Is the ratio of males to females under one year of age in a given population usually
expressed as the number of males for every 100 females.
3.7.6 Elderly Population
According to the international definition, elderly is a person aged 65 years and above.
However, according to the Tanzania National Ageing Policy, elderly is a person aged
60 years and above.
3.7.7 Age Dependency Ratio It is the ratio of persons in the “dependent” ages (generally under 15 and over 64) to those in the “economically active” ages (15 – 64) in a population.