2. Measures of Urbanization
Degree or Level of
Urbanization
Tempo of Urbanization
City Population
Distribution
The Concentration and
Dispersion of Population
3. Measures
Degree or
Level of
Urbanizati
on
relative
distribution of
population
between rural
and urban
areas
Percent
Urban
Urban/Ru
ral Ratio
the absolute and
relative size of
urban centers
Size of
Locality of
Residence
of the
Median
Inhabitant
Mean City
Population
Size
Tempo of
Urbanizati
on
Annual
Change of
Percentag
e Points
Average
Annual
Rates of
Change of
the
Percent
Urban
Difference
of Urban
and Rural
Rates
Change in
Size of
Place of
Residence
of the
Median
Inhabitan
t
5. Level/Degree of Urbanization:
Percent Urban
Defined as relative number of people who
live in urban areas.
• Commonly used index
• Easy to calculate and interpret
• Higher the percentage of urban
population to total population higher is
the level of urbanization.
Disadvantage of this index
• once a country achieves a high
proportion of urban population, further
increase in the % urban is negligible,
although the 'urban process' may
continue in the sense that the size of
cities continues to increase.
• This index is also affected by the changes
and differences in the definition of urban.
• PU = Ui/Pi*100
• Ui= Urban population of an area; and
• Pi=Total population of an area.
Measures
Degree or
Level of
Urbanization
relative
distribution of
population
between rural and
urban areas
Percent
Urban
Urban/Rural
Ratio
theabsoluteand
relativesizeof
urban centers
Size of
Localityof
Residence of
the Median
Inhabitant
Mean City
Population
Size
Tempo of
Urbanization
Annual
Change of
Percentage
Points
Average
Annual Rates
of Change of
the Percent
Urban
Differenceof
Urban and
Rural Rates
Change in
Size of Place
of Residence
of the
Median
Inhabitant
6. Level/Degree of Urbanization:
Urban / Rural Ratio
• a simple index and
• Measures :relative number of urbanites
for each rural person in an areal unit
– Lower limit=0 (when the whole population is
rural)
– Index value 1 when 50 percent of the
population is rural,
– In theory the upper limit would be infinite
when the country has no rural population;
• however in such cases it can be assumed
that one person is in rural live in thereby
making the upper limit of the index
equal to the total size of the population
minus one.
• This index is useful for estimating
changes in the urbanization process.
• Disadvantage: This is also affected by
changes and differences in the
definition of urban.
Ui/Ri*100
Ui= Urban population of a country; and
Ri= Rural population of a country
Example :
Measures
Degree or
Level of
Urbanization
relative
distribution of
population
between rural and
urban areas
Percent
Urban
Urban/Rural
Ratio
theabsoluteand
relativesizeof
urban centers
Size of
Localityof
Residence of
the Median
Inhabitant
Mean City
Population
Size
Tempo of
Urbanization
Annual
Change of
Percentage
Points
Average
Annual Rates
of Change of
the Percent
Urban
Differenceof
Urban and
Rural Rates
Change in
Size of Place
of Residence
of the
Median
Inhabitant
7. Level/Degree of Urbanization:
Size of Locality of Residence of the Median Inhabitant
• the size of the locality where the median
inhabitant lives.
– the population of a country is ordered
according to the size of localities- from the
smallest to the largest or vice-versa, and
– each inhabitant is assigned a rank from
number one to the total population number,
– the index denotes the size of the locality
inhabited by the person occupying the
fiftieth percentile, i.e., with the rank equal
to one half of the population of the country.
Higher the city size of the median inhabitant, the
higher is the level of urbanization.
• Takes into account the actual size of locality
Limitation:
• the value of the index can vary over time or
between countries solely because of the city-size
distribution.
• cannot be calculated: units where rural is >50%
and no classification of rural localities exists
(Arriaga, 1975).
• Where:
– MI :Median Inhabitant
– PPi :The cumulative percent of population for the
locality-size category just under 50 per cent;
– PPi+1 :The cumulative per cent of the next locality-
size category;
– Qi :Lowerer limit of the locality-size category i;
and
– Qi+1 :Upper limit of the locality size of category
i+1.
PP-PP
PP-50
)Q-Q(+Q=MI
i1+i
i
i1+ii
705,2
30.4978.57
30.49
4,25.499,2
-50
99)-(4,999+=MI
Computation of size of locality of residence of Median Inhabitant
Locality Size
Categories
Populatio
n
Percent Percent
Cumulati
ve
Distributi
on
Total 34,923,129 100.00
< 1,000
1,000 - 2,499
2,500 - 4,999
5,000 - 99,999
10,000 and over
12,222,347
4,995,644
2,959,460
8,233,426
6,512,232
35.00
14.30
8.48
23.57
18.65
35.00
49.30
57.78
81.35
100.00
8. Level/Degree of Urbanization:
Mean City Population Size
• It takes into account the size of cities, unlike
percent urban and urban/rural ratio, and
consequently give different results when applied
to countries or areas where the percent urban is
the same but the size of cities is different.
• This index tells the size of the city in which the
average number of person lives.
• The calculation of this index would require
information on every urban-settlement in the
country.
Where,
• Ci is the population of city i;
• n is the total number of cities; and
• P is the total population of the country.
P
C
=MC
2
i
n
=1i
Cities (i)
(1)
Population (thousands)(Ci)
(2)
Square of population (Ci) (Ci)
(3)= (2) (2)
Ludhina
Amritsar
Jalandhar
Patiala
Bathinda
Pathankot
Hoshiarpur
Moga
Abohor
Batala
1043
709
509
254
159
128
123
111
107
103
1087849
502681
259081
64516
25281
16384
15129
12321
11449
10609
Totals 3246 2005300
Total population of Punjab 20282 411359524
Index of Mean city population size (thousands) =
Σ Cii
2 / Σ Pi = 2005300 / 20282 = 99
Σ Cii
2 / Σ Ci = 2005300 / 3246 = 618.
Note: Not a very
suitable example as
the table contains
class I cities only so
formula has been
modifies slightly
9. Level/Degree of Urbanization:
Mean City Population Size (contd.)
• Even if, cities over a certain size (such as 20,000 and
over or 50,000 and over) are considered, the index is
not significantly affected.
• This summarized version of the index can be
interpreted as a product of two aspects of
urbanization,
– (i) mean city population size (represented by the first
factor in the above formula); and
– (ii) proportion of population in cities (represented by
the second factor in the above formula) (class I cities).
• The change in this index can be decomposed into the
two components and thus the index is used to
explain a change in the degree of urbanization.
• Ranges= 0-100
• 0, when there is no city and
• 100, when all people are concentrated in a single city.
P
C
C
C
=MC
i
u
1=i
i
u
1=i
2
i
u
1=i
Where,
Ci is the population of city i;
n is the total number of cities; and
P is the total population of the country.
u is the number of cities over any
chosen limit.
Cities (i)
(1)
Population
(thousands)(Ci)
(2)
Square of population
(Ci) (Ci)
(3)= (2) (2)
Ludhina
Amritsar
Jalandhar
Patiala
Bathinda
Pathankot
Hoshiarpur
Moga
Abohor
Batala
1043
709
509
254
159
128
123
111
107
103
1087849
502681
259081
64516
25281
16384
15129
12321
11449
10609
Totals 3246 2005300
Total population
of Punjab
20282
Index calculation:
(i) Proportion of population in class I cities = Σ Ci / P = 3246 / 20282 = 0.160;
(ii) Mean city population size (thousands) = Σ Cii
2 / Σ Ci = 2005300 / 3246 = 618.
(iii) Index of Mean City Population Size (thousands) = Σ Cii
2 / P=2005300 / 20282 = 99
10. • The index also can be calculated from
aggregated data of cities by city-size
categories.
• If the largest city-size category is open-
ended and the number of cities included
in it is unknown, an estimate of the
average city size should be used.
This index may be useful
• (i) for comparing the urbanization status
within a country;
• (ii) for international comparisons of city
size.
• (iii) In cases where states or countries
have the same proportion of population
living in cities over a certain size, this
index detects differences in the size of
cities.
(I) If the number of cities in each category is
known:
• Where,
Kj is the population in the city-size category j;
mj is the number of cities in the city-size category j;
s is the total number of city-size categories; and
P is the total population.
(II)If the number of cities in each category is
not known:
• Where,
zj is the geometric mean of the limits of the city-size
category j;
Kj is the population in the city-size category j;
s is the total number of city-size categories; and
P is the total population.
P
m
k
=MC
j
2
j
s
1=j
a
P
zk
=MC
jj
s
1=j
b
11. Index of City Concentration
• Based on the concept of the Mean City
Population Size.
• Compares the achieved mean city
population size with the possible maximum
city size in a population.
• The possible maximum is the total
population, i.e., when everyone lives in a
city.
– Ranges= 0-100
– 0, when there is no city and
– 100, when all people are concentrated in a
single city.
Limitation
• Since this index is based on the index of
Mean City Population Size, it is also
affected by the delimitation of city
boundaries.
• In this example: 48. 75
• Approximately 49% of the urban
population in Punjab are concentrated in
its Class I cities.
where Ci is the population of city i, u is
the number of cities included as
urban, and P is the total population.
100
P
C
=CC 2
2
i
u
1=i
Cities (i)
(1)
Population
(thousands)(Ci)
(2)
Square of population
(Ci) (Ci)
(3)= (2) (2)
Ludhina
Amritsar
Jalandhar
Patiala
Bathinda
Pathankot
Hoshiarpur
Moga
Abohor
Batala
1043
709
509
254
159
128
123
111
107
103
1087849
502681
259081
64516
25281
16384
15129
12321
11449
10609
Totals 3246 2005300
Total population of
Punjab
20282 411359524
12. Thus
• There is no one ideal index for measuring the degree of urbanization.
• Percent Urban and Urban-Rural Ratio are simple indices and are easily
calculated and interpreted, but they don't take account of city size
distribution.
• The size of Locality of Residence of Median Inhabitant takes into account
only the size of cities, and is affected by the distribution of cities.
• Mean City Population Size in its pure form does not tell anything about
the dimension of urbanization tapped by the per cent urban or urban-
rural ratio, i.e., the relative distribution of population between urban and
rural areas but gives a mean size of cities which can be considered a
product of the urban proportion of the population and the average city
size of residence of the urban population.
• When data on city size are available, the last two indices are better. The
use of different indices, therefore, will depend upon the nature of data
available and the purpose of the study.
13. Tempo/ Speed/ Rate of Urbanization
• Refers to the change in the level of urbanization
over a specified period of time.
• The speed of urbanization would be the change
registered in indices of level of urbanization over
a period of time.
• the tempo can be measured
– either as an absolute change in percentage points or
– as a rate of change in the percent urban between
two dates.
14. Tempo of urbanization
• Annual change of
percentage points
• But it is affected by the
degree of urbanization
reached
• as the countries with a
very high level of
urbanization cannot
show much further
change despite the
possibility that the
process of urban
growth can continue.
TA =Tempo of urbanization
n= Number of years
PU=Percent urban at the years t and t+n
)(
1 tnt
PUPU
n
TA
1981
% Urban
19.51
1991 26.92 TA= 0.741
2001 25.96 -0.096
15. Annual change of percentage
points
Average Annual Rates of Change of
the Percent Urban: LINEAR
Where
TRa= Tempo of urbanization.
n= Number of years.
PU=Percent urban at the year t and t+n.
TA =Tempo of urbanization
n= Number of years
PU=Percent urban at the years t and t+n
tnt
PUPU
n
TA
(
1 100)-
PU
PU
(
n
1
=TR t
+nt
a 1
100ln
1
tPU
ntPU
ne
TR
Average Annual Rates of
Change of the Percent Urban:
EXPONENTIAL
1981 19.51
1991 26.92
2001 25.96
TA TR (Linear) TR (Exponential)
1981-91 0.741 3.798052 3.219424
1991-2001 -0.096 -0.35661 -0.36313
16. Growth of Urban Population and its
Components
• Assumption and procedure of calculating
average annual growth rate of urban
population is same as the average annual
growth rate of total population,
i.e., linear, exponential, and geometric
• Here we consider only urban population
instead of the total population.
• The most frequently used assumptions are
linear and exponential pattern of change.
• exponential model: When the time period
involved is more than 10 years and the gap
between two points of time is not the
same.
• The linear model: When the time period is
not more than 10 years, a linear model can
be used.
• The linear model, however, will produce
consistently higher rate of urban
population growth.
• Linear
• Exponential
Ut+n = Ut eUr.n
1001-
U
U
n
1
=U t
n+t
r
17. Tempo of urbanization
• refers to speed of urbanization and is measured as change registered in the level
or degree of urbanization over the years.
• not uniform over the years and shows fluctuating trend (1901-1981) and a
declining trend during 1981-91, 1991-2001.
18. Note:
• All calculations should be made using the same assumption
whenever comparisons are planned.
• If the tempo of urbanization is measured as a percent, it will
tend toward zero as the urban population reaches the 100 per
cent level, since the urban and total population growth rates
would become the same.
19. Pace of Urbanisation
• Urbanisation in India has been relatively slow compared to many
developing countries.
• The percentage of annual exponential growth rate of urban
population (table 5) reveals
– India it grew at faster pace from the decade 1921-31 to until 1951.
– it registered a sharp drop during the decade 1951-61.
– The decades 1961-71 and 1971-81 showed a significant improvement
in the growth which has thereafter steadily dropped to the present
level 2.7.
• .
20. Measures
City Population
Distribution
Distribution of Urban
Population by Urban
Locality Size Class
Index of City
Distribution
The Concentration
and Dispersion of
Population
The Primacy Index
Index of City
Concentration
21. City Population Distribution:
Distribution of urban population by
urban locality size class
• A very simple and frequently used measure to show the dominance of
large-size cities is to present the percentage distribution of urban
population by locality size class of urban centers.
• Indian census classifies the urban centers in the following six population
size classes:
• Class- Population Size
I > 100,000
II 50,000 - 99,999
III 20,000 - 49,999
IV 10,000 - 19,999
V 5,000 - 9,999
VI <5,000
23. City Population Distribution:
Index of City Distribution
• there exists a regularity
between the size of the city
and its rank and this
relationship between the
sizes of the cities and their
ranks is known as Rank Size
Rule.
• According to this rule, it is
possible to adjust the
distribution of cities with a
function, which relates the
population size of any city to
its rank and to the
population size of the largest
city.
Where,
Ck represents the population of the city
ranked in place k from the largest city to the
smallest city in population size.
C1 is population of the largest city.
k is the rank order.
Z is a constant = the index of city distribution.
2
lnln
ln(k)
(k))
C
C(
=Z k
1
𝐶 𝑘 = 𝐶1. 𝐾−𝑍
24. • Value of Z characterizes a
city distribution.
• The greater the value of Z,
the greater is the
concentration of population
in the largest cities relative
to the smallest cities.
• Advantage
it facilitates the international
comparison of city size
distribution by reducing
them to a single value as
well as in the change in the
concentration over a period
of time.
Steps in calculating constant Z in the Rank-Size
Formula for Jharkhand, 2011
Cities
Populatio
n rank
C1/C
k
ln(C1
/Sk) ln(K)
(ln(K)
)*
(ln(K)
)
ln(C1
/Sk)*
ln(K)
Dhanbad 1161651 1 1 0 0 0 0
Ranchi 1074440 2 1.08 0.08 0.69 0.48 0.05
Jamshedpur 629659 3 1.84 0.61 1.10 1.21 0.67
Bokaro Steel
City 413934 4 2.81 1.03 1.39 1.92 1.43
Mango 224002 5 5.19 1.65 1.61 2.59 2.65
Deoghar 203116 6 5.72 1.74 1.79 3.21 3.12
Aditya 173988 7 6.68 1.90 1.95 3.79 3.69
Hazaribagh 142494 8 8.15 2.10 2.08 4.32 4.36
Chas 141618 9 8.20 2.10 2.20 4.83 4.62
Giridih 114447 10 10.15 2.32 2.30 5.30 5.34
27.6525.95
Z 0.94
City Population Distribution:
Index of City Distribution
25. The Concentration and Dispersion of
Population : Primacy Index
• Relate to the concentration and
dispersion of urban population.
• Primacy Index: Having the Z value also
allows the calculation of primacy index.
• The primacy index shows the dominance
of the largest city with respect to the
second largest city or subsequent cities.
• Assuming that the exponent Z of the
rank (constant Z in the rank-size formula)
is one, the size of any city is equal to the
largest city divided by its rank. Under this
condition, the population of the largest
city is equal to the population contained
in the second, third and a fraction of the
fourth ranked cities.
• The primacy index (Davis, 1962) can be calculated for a
two-city, a four-city or even eleven-city Primacy Index.
The Four-City Primacy Index is given as
• where, C1 is the population of the largest city and CK (for
k = 2, 3, and 4) represents the population of the second,
third and fourth ranked cities respectively.
• The Eleven-City Primacy Index is given by
• where C1 is the population of the largest city and CK (for
K = 2, 3,..., 11) represents the population of the second,
third ... and eleventh ranked cities respectively.
C
C=IP
k
4
2=k
1
4
C
C2
=IP
k
11
2=k
1
11
26. • If the assumption is valid, the addition of population in the second, third
and fourth ranked cities would be 13/12 of the first city (1/2 + 1/3 + 1/4 =
13/12).
• Thus, the division of the first city by the summation of the population of the
three following cities should be close to one if they follow the rank-size
rule.
• Thus the index measures the concentration of the first city in relation to the
remaining three cities.
• The greater the index value, the greater is the concentration in the largest
city. The concentration can also be analysed by comparing the actual size of
city with the expected size by the rank-size rule.
• The comparison of distribution with the expected distribution will show
which cities contain relatively higher concentration of people.
27. Rank-Size Rule: explain size and
growth patterns of cities
• Zipf (1949) put forth a “law” to explain the size and ranking of cities in a country. Simply stated, his law is that
– if the cities of a country are ordered by population size, the largest city will be twice as large as the second largest city, three
times as large as the third largest city, four times as large as the fourth largest city, and so forth.
• His law is expressed by the following formula:
–
– .....................(I)
• where Pi is the population of the city, ri is the rank of the city, and K is the size of the largest city. With an addition
of a constant (n), this formula can be generalized to create the rank-size rule as follows:
•
– .................................(II)
–
• Therefore, Zipf’s law is a special case of the rank size rule when n =1.
• Zipf’s law and the rank-size rule can be tested empirically by plotting the logarithm of the rank of the cities against
the logarithm of their populations. The resulting slope should be -1, showing an inverse relationship between the
logarithm of the size of city and the logarithm of its rank.
• For years researchers have been trying to explain the consistency of Zipf’s law. Although it does not always
accurately describe the size and ranking of cities, it is, more often than not, correct (Brakman et al., 1999; Gabaix,
1999; Reed,1988) If cities follow Gibrat’s law (Gabaix, 1999) and grow
• at the same rate regardless of size, the rank-size rule will at some point describe the size and rankings of the cities
within a country.
• However, there is a tendency for the rank-size rule not to hold true in the case of primate cities that are national
capitals (Cifuentes, 2002).
28. Measures
City Population
Distribution
Distribution of Urban
Population by Urban
Locality Size Class
Index of City
Distribution
The Concentration
and Dispersion of
Population
The Primacy Index
Index of City
Concentration
29. City Population Distribution:
Distribution of urban population by urban locality size class
• A very simple and frequently used measure
• Shows the dominance of large-size cities
• percentage distribution of urban population by locality size class of urban
centers.
• Indian census classifies the urban centers in the following six population
size classes:
• Class- Population Size
I > 100,000
II 50,000 - 99,999
III 20,000 - 49,999
IV 10,000 - 19,999
V 5,000 - 9,999
VI <5,000
31. City Population Distribution:
Index of City Distribution
• there exists a regularity between
the size of the city and its rank
and this relationship between the
sizes of the cities and their ranks
is known as Rank Size Rule.
• According to this rule, it is
possible to adjust the distribution
of cities with a function, which
relates the population size of any
city to its rank and to the
population size of the largest city.
Where,
Ck represents the population of
the city ranked in place k from the
largest city to the smallest city in
population size.
C1 is population of the largest city.
k is the rank order.
Z is the index of city distribution.
2
lnln
ln(k)
(k))
C
C(
=Z k
1
32. • Value of Z characterizes a city
distribution.
• The greater the value of Z, the
greater is the concentration of
population in the largest cities
relative to the smallest cities.
• Advantage
it facilitates the international
comparison of city size
distribution by reducing them
to a single value as well as in
the change in the
concentration over a period of
time.
Steps in calculating constant Z in the Rank-Size
Formula for Jharkhand, 2011
Cities
Populati
on rank
C1/C
k
ln(C1
/Sk) ln(K)
(ln(K)
)*
(ln(K)
)
ln(C1
/Sk)*
ln(K)
Dhanbad
116165
1 1 1 0 0 0 0
Ranchi
107444
0 2 1.08 0.08 0.69 0.48 0.05
Jamshedpur 629659 3 1.84 0.61 1.10 1.21 0.67
Bokaro Steel City 413934 4 2.81 1.03 1.39 1.92 1.43
Mango 224002 5 5.19 1.65 1.61 2.59 2.65
Deoghar 203116 6 5.72 1.74 1.79 3.21 3.12
Aditya 173988 7 6.68 1.90 1.95 3.79 3.69
Hazaribagh 142494 8 8.15 2.10 2.08 4.32 4.36
Chas 141618 9 8.20 2.10 2.20 4.83 4.62
Giridih 114447 10 10.15 2.32 2.30 5.30 5.34
27.6525.95
Z 0.94
City Population Distribution:
Index of City Distribution
34. The Concentration and Dispersion of
Population : Primacy Index
• Relate to the concentration and
dispersion of urban population.
• Primacy Index: Having the Z value
also allows the calculation of
primacy index.
• The primacy index shows the
dominance of the largest city with
respect to the second largest city or
subsequent cities.
• Assuming that the exponent Z of
the rank (constant Z in the rank-size
formula) is one, the size of any city
is equal to the largest city divided
by its rank. Under this condition,
the population of the largest city is
equal to the population contained
in the second, third and a fraction
of the fourth ranked cities.
• The primacy index (Davis, 1962) can be calculated for a
two-city, a four-city or even ten-city Primacy Index. The
Four-City Primacy Index is given as
• where, C1 is the population of the largest city and CK (for
k = 2, 3, and 4) represents the population of the second,
third and fourth ranked cities respectively.
• The Eleven-City Primacy Index is given by
• where C1 is the population of the largest city and CK (for
K = 2, 3,..., 11) represents the population of the second,
third ... and eleventh ranked cities respectively.
C
C=IP
k
4
2=k
1
4
C
C2
=IP
k
11
2=k
1
11
35. • If the assumption is valid, the addition of
population in the second, third and fourth ranked
cities would be 13/12 of the first city (1/2 + 1/3 +
1/4 = 13/12).
• Thus, the division of the first city by the
summation of the population of the three
following cities should be close to one if they
follow the rank-size rule.
• Thus the index measures the concentration of the
first city in relation to the remaining three cities.
• The greater the index value, the greater is the
concentration in the largest city. The
concentration can also be analysed by comparing
the actual size of city with the expected size by the
rank-size rule.
• The comparison of distribution with the expected
distribution will show which cities contain
relatively higher concentration of people.
Rank City 2011
Ran
k City 2001
1 Mumbai 18394 1 Mumbai 16434
2 Delhi 16349 2 Delji 13850
3 Kolkata 14057 3 Kolkata 13205
4 Chennai 8653 4 Chennai 6560
5 Banglore 8520 5 Hyderabad 5742
6 Hyderabad 7677 6 Banglore 5701
7 Ahmedabad 6357 7 Ahmedabad 4525
8 Pune 5057 8 Pune 3760
9 Surat 4591 9 Surat 2811
10 Jaipur 3046 10 Kanpur 2715
11 Kanpur 2920 11 Jaipur 2322
PI4 0.4709 0.4889
PI11 0.2382 0.2686
Notes de l'éditeur
This index establishes the size of the locality where the median inhabitant lives (Shryock and Siegel, 1971).
The concept is similar to that of median age of population, except that this index uses the size of localities rather than age. For example, if the population of a country is ordered according to the size of localities where people live from the smallest to the largest or vice-versa, and each inhabitant is assigned a rank from number one to the total population number, then the index denotes the size of the locality inhabited by the person occupying the fiftieth percentile, i.e., with the rank equal to one half of the population of the country.
Formula same as L+(n/2-cfpc/f mc)*ci
This index establishes the size of the locality where the median inhabitant lives (Shryock and Siegel, 1971).
Calculated same as mean age
This index takes into account the size of cities, unlike percent urban or urban/rural ratio. It tells the size of the city in which the average urban dweller lives. This index has the same concept as the mean age of a population and the calculation is similar. It is defined as The calculation of this index requires data on every settlement in the country. If instead of all cities, cities over a certain population size (over 50,000 or 100,000) are taken, this index is not significantly affected. This index can be considered to be a product of two parts: the mean city population size and the proportion of population in cities. Hence change in this index over time can be decomposed due to changes in these two dimensions. The lower limit of this index is very close to 1 when the population of the country is completely dispersed without any city and the upper limit is the total population when the whole population lives in one city
i. Annual growth rate of urban population size using linear or exponential curve
ii. Annual change of urban percentage points using linear or exponential rates
iii. Annual change in urban/rural ratios using linear or exponential curves