Chapter 1 Introduction to statistics, Definitions, scope and limitations.pptx

S A N T O S H M A R A H A T T A
D E P A R T M E N T O F A G R O N O M Y
A G R I C U L T U R E A N D F O R E S T R Y U N I V E R S I T Y
R A M P U R , C H I T W A N , N E P A L
Introduction to Statistics:
Definitions, Scope and Limitations

Meaning and definition
 The term “statistics” is used in two senses:
 First in plural sense meaning a collection of numerical facts or
estimates—the figure themselves.
 Secondly, as a singular noun, the term ‘statistics’ denotes the
various methods adopted for the collection, analysis and
interpretation of the facts numerically represented.
 In singular sense, the term ‘statistics’ is better described as
statistical methods.
 In our study of the subject, we shall be more concerned with the
second meaning of the word ‘statistics’.

 A.L. Bowley defines
 “Statistics may be called the science of counting”.
 “Statistics may be called the science of averages”.
 According to King,
 “The science of statistics is the method of judging collective, natural or
social, phenomenon from the results obtained from the analysis or
enumeration or collection of estimates”.
 In the words of Croxton & Cowden,
 “Statistics may be defined as the collection, presentation, analysis and
interpretation of numerical data”.

 Horace Secrist has defined
 “By statistics we mean aggregates of facts affected to a marked extent
by a multiplicity of causes numerically expressed, enumerated or
estimated according to reasonable standards of accuracy collected
in a systematic manner for a pre-determined purpose and placed in
relation to each other”.
 Statistic should possess the following characteristics.
 Statistics are aggregate of facts. A single weight of fingerling i.e. 20
or 30 g is not statistics, a series of weight are.
 Statistics are affected to a marked extent by a multiplicity of causes.
A number of causes affect statistics in a particular field of enquiry,
e.g., in production statistics are affected by climate, soil, fertility,
availability of raw materials and methods of quick transport.

 Statistics are numerically expressed, enumrated or estimated. The
subject of statistics is concerned essentially with facts expressed in
numerical form (quantitative) but not qualitative descriptions.
 Statistics are numerated or estimated according to reasonable
standard of accuracy. The figures should be counted or estimated
according to reasonable standards of accuracy.
 Statistics should be collected in a systematic manner for a
predetermined purpose. The statistical methods to be applied on the
purpose of enquiry since data are always collected with some
purpose.
 Statistics should be capable of being placed in relation to each
other. The collected figure should be comparable and well-connected
in the same department of inquiry. Weight of fingerlings are to be
compared only with the corresponding weight of fingerlings with
different species, and not with, say, length of fingerlings.


Functions of statistics
 To present facts in a definite form : Without a statistical study our
ideas are likely to be vague, indefinite and hazy.
 To simplify unwieldy and complex data : Complex data may
be simplified by presenting them in the form of a table, graph or
diagram, or representing it through an average etc.
 To use it as a technique for making comparisons : The significance of
certain figures can be better appreciated when they are compared with
others of the same type.
 To enlarge individual experience : An individual’s knowledge is limited
to what he can observe and see.
 To provide guidance in the formulation of policies : The purpose of
statistics is to enable correct decisions, whether they are taken.
 To enable measurement of the magnitude of a phenomenon :

Importance of statistics: some areas
o Planning is indispensable for better use of nation’s resources.
Statistics are indispensable in planning and in taking decisions
regarding export, import, and production etc., Statistics serves as
foundation of the super structure of planning.
o Statistics helps the business man in the formulation of polices with
regard to business. Statistical methods are applied in market and
production research, quality control of manufactured products.
o Statistics is indispensable in economics. Any branch of economics
that require comparison, correlation requires statistical data for
salvation of problems.
o In collecting the information about population, military strength
etc., Administration is largely depends on facts and figures thus it
needs statistics

o Bankers, stock exchange brokers, insurance companies all make
extensive use of statistical data.
o Problems relating to poverty, unemployment, food storage, deaths due to
diseases and shortage of food etc., cannot be fully weighted without the
statistical balance. Thus statistics is helpful in promoting human welfare
o Statistics are a very important part of political campaigns as they lead up
to elections. Statistics are used to calculate and illustrate the results in
percentages and to calculate the margin for error.
o Thus
o Statistics plays an important role in our daily life, it is useful in almost
all sciences – social as well as physical
o The statistical methods can be and are being followed by both
educated and uneducated people
o In many instances we use sample data to make inferences about the
entire population.
Importance of statistics: some areas

In agriculture
o In determining the required doses of fertilizer for a particular crop
and crop land.
o In estimating the losses incurred by particular pest and the yield
losses due to insect, bird, or rodent pests statistics is used in
entomology.
o In making data about decision on pesticides applications
o In determining and estimating the irrigation required by a crop per
day, per base period.
o In soil chemistry also statistics helps classifying the soils basing on
their analysis results, which are analyzed with statistical methods.
o Agricultural economists use forecasting procedures to determine the
future demand and supply of food

In agriculture
o Animal scientists use statistical procedures to aid in analyzing data
for decision purposes.
o Agricultural engineers use statistical procedures in several areas,
such as for irrigation research, modes of cultivation and design of
harvesting and cultivating machinery and equipment.
o Thus, In agricultural research, Statistical tools have played a
significant role in the analysis and interpretation of data.

Statistics
 Descriptive statistics
 Inferential statistics
Population
Sample
Study about the sample
To describe about the
population based on the
information of sample
Statistic: characteristics of sample, mean (𝑥)
Parameter: characteristics of
population, average (𝜇)

Limitations of Statistics
o Statistics does not study qualitative phenomenon
o Statistics does not study individuals
o Statistics laws are not exact laws
o Statistics does not reveal the entire information
o Statistics is liable to be misused
o Statistical conclusions are valid only on average base

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