This is an explanation of urban functional classification based on arithmetic mean and standard deviation as proposed by Howard Nelson in citing proper practical examples.

1. Special Lecture on
Nelson’s Dominant and Distinctive Function
Presented by
Dr. Nazrul Islam
Associate Professor
Department of Geography
Cooch Behar Panchanan Barma University
1/19/2022 Dr. Nazrul Islam

2. Definition of Urban Centres
Definition of urban place was provided by Office of
Population Censuses and Surveys (OPCS) 1981 and Key
Statistics for Urban Areas, 1984. According to them
urban areas are made up of:
1. Permanent structures and the land on which they are
situated
2. Transportation corridors (roads, railways and canals)
which have built-up sites which are less than 50 metres
apart
3. Transportation features such as railway yards,
motorway services areas and car parks (operational
airfields and airports are also included)
4. Mineral workings and quarries
5. Any area completely surrounded by built-up sites
31-12-2021 Dr. Nazrul Islam

3. Definition of Urban Area
Again, For the Census of India 2011, the definition of
urban area is as follows;
1. All places with a municipality, corporation, cantonment
board or notified town area committee, etc.
2. All other places which satisfied the following criteria:
i) A minimum population of 5,000;
iI) At least 75 per cent of the male main working
population engaged in non-agricultural pursuits; and
iii) A density of population of at least 400 persons per sq.
km.
31-12-2021 Dr. Nazrul Islam

4. Classification of Urban places on the basis of Functions
Urban centres vary in their functions, location, size and in their social
composition, culture and heritage also. There are several methods,
ways and means to classify urban centres. Out of all these bases of
classification, the variable of ‘function’ is widely accepted and reliable
method of defining urban places. Several authors have classified urban
centres based on functions as follows
• In 1921, M. Aurousseau classified towns into six classes with twenty
eight sub types.
• Chauncy D. Harris in his paper ‘A Functional Classification of Cities in
the United States (1943)’
• Howard Nelson’s Classification based on Statistics i.e. Mean and SD
• Amrit Lal (1959) used the location quotient (L.Q) method to determine
the functional classification of the Class I cities of India.
• Qazi Ahmad (1965) used 62 variables to classify 102 Indian cities on
the basis of their functions.
• Ashok Mitra (1971, 1973) used seven categories of workers as
variables grouped into three major functional types, such as
manufacturing, trade, transport and services.
31-12-2021 Dr. Nazrul Islam

5. Howard Nelson’s Classification
• Nelson removed the shortcomings of the earlier classifications based on
the objectivity of the types of workers. In his research paper ‘A Service
Classification of American Cities’(1955) has taken major industry
groups as listed in the 1950 Census of Population for standard
metropolitan areas, urbanized areas and urban places of 10,000 or more
population. He omitted the little significance groups like agriculture and
construction, and finally, arrived at the nine activity groups
(manufacturing; retail; professional services; wholesale; personal service;
public administration; transport and communication; finance, insurance,
real estate and mining). He did find a definite tendency for the
percentages employed in some activities vary with city size. The question
– ‘When is a city specialized?’ was solved by using a statistical technique
– the Mean and Standard Deviation (SD).
31-12-2021 Dr. Nazrul Islam

6. What is Dominant and Distinctive Analysis?
• Dominant and distinctive Analysis is an important
technique to study and/or identify the dominant
and distinctive attributes from the group of
attributes in a particular region or area. This
analysis is mainly used in the field of Urban
geography, Industrial geography and Agricultural
geography.
• e.g. Dominance and distinctive of different crop
production in an area or workers engaged in
different types of activities of an area.
• So, Dominant function means the attributes
which shares the highest proportion (%) is
identified as most influential one.
1/19/2022 Dr. Nazrul Islam

7. • Distinctiveness is a character which makes an area or region
different from others. Nelson, an Urban Geographer
attempted to measure distinctiveness of the functions of
industrial category of workers in different urban centres.
Nelson has taken into consideration the Arithmetic mean as
well as standard deviation. He considered the % of the workers
greater than the Arithmetic Mean +1SD as the bench mark for
being as distinctive function. The following classes were taken
into consideration.
1/19/2022 Dr. Nazrul Islam
Range of Classes Scale of Distinctiveness
1st Order
2nd Order
3rd Order

8. What is Mean (x̄) ?
• The ‘arithmetic mean’ is an easiest and most
commonly used measure of ‘central tendency’ and
simply referred to an ‘average’. It is denoted by (x̄).
সমজাতীয় রাশিমালার অন্তর্ভু ক্ত রাশিগুললার সমশিলে
রাশির মমাট সংখ্যা দ্বারা র্াগ েরলল প্রাপ্ত
র্াগফললে গড় বা Mean বলে।
• The mean is found by adding all of the numbers
together and dividing by the number of items in the
set. For Example: (10 + 10 + 20 + 40 + 70)/ 5 = 30.
31-12-2021 Dr. Nazrul Islam

9. Formulae of Arithmetic mean
Dr. Nazrul Islam

10. What is Standard Deviation (σ) সম্যক বা প্রম্াণ ববচ্যযবি
• Definition: The standard deviation is a statistic that
measures the dispersion of a dataset relative to its mean
and is calculated as the square root of the variance.
• Standard deviation is the square root of the arithmetic
average of the square of all the deviations taken from mean.
Shortly it is known as “Root mean square deviation” It is
denoted by Greek small letter Sigma (σ).
It was first used by Karl Pearson in 1893.
Standard deviation is the measure of dispersion of a set of data
from its mean. It measures the absolute variability of a
distribution; higher the dispersion or variability, the greater
is the standard deviation and greater will be magnitude of
the deviation of the value from their mean.
সম্যক বা প্রবম্ি ববচ্যযবি:
• গড় মেলে শবচ্ভযশতর বগুসমশির গলড়র বগুমূললে সমযে বা প্রশমত শবচ্ভযশত
বলল | এই শবচ্ভযশত পভলরাপভশর গাশিশতে শিয়লম েরা হয় এবং ইহা এেটি
পশরমাশজ
ু ত ও পশরলিাশিত শবচ্ভযশত |
31-12-2021 Dr. Nazrul Islam

11. Formulae of SD
A) Individual Series: a) Standard deviation (Direct Method)
B) Discrete Series: a) Standard deviation (Direct method)
C) Continuous Series a) Standard Deviation by Shortcut Method
31-12-2021 Dr. Nazrul Islam

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16. Mapping of Nelson’s Dominant and Distinctiveness Function
31-12-2021 Dr. Nazrul Islam