Statistics Introduction

STATISTICS INTRODUCTION

Dr.R.VARADHARAJAN
Associate Professor in Statistics
Department of MBA
Vels University, chennai.

Dr.R.VARADHARAJAN, MBA DEPT, VELS UNIVERSITY

Origin and Development
 It is not a new discipline.
 It has been used right from the existence
of life on earth, through its use was very
much limited.
 In the good old days Statistics was
regarded as the ‘Science of Statecraft’
and was the by – product of the
administrative activity of the state.
2


Origin and Development
Contd…
 It has been the traditional function of the
governments to keep records of population,
births, deaths, taxes, crop yields and many
other types of activities

 Also Statistics originated as a science of
kings.

3


Definition:

 “Statisticsmay be called the science of
counting” – A.L.BOWLEY

 According to Croxton and Cowden
Statistics may be defined as “The science
of collection, organization, presentation,
analysis and interpretation of numerical
data”.


Descriptive Statistics
 Descriptive statistics are methods for
organizing and summarizing data.
 For example, tables or graphs are used to
organize data, and descriptive values such
as the average score are used to summarize
data.
 A descriptive value for a population is
called a parameter and a descriptive value
for a sample is called a statistic.
5


Inferential Statistics
 Inferential statistics are methods for using
sample data to make general conclusions
(inferences) about populations.
 Because a sample is typically only a part of
the whole population, sample data provide
only limited information about the
population. As a result, sample statistics are
generally imperfect representatives of the
corresponding population parameters. 6


Collection:

 Utmost care must be exercised in
collecting data because they form the
fundamental of Statistical analysis. If the
are faulty, the conclusions drawn can
never reliable.


Organization:

A large mass figures that are collected
from a survey frequently needs
organization.
 The collected data must be edited very
carefully so that the omissions,
inconsistencies, irrelevant answers and
wrong computations in the returns from a
survey may be corrected or adjusted


Organization Contd…

 Thenext step is to classify them .
(Arrange the data according to some
common characteristics)

 The last step in the organization is
tabulation.
(Arrange the data in rows and columns)


Presentation:
 After the data have been collected and
organized they are ready for presentation.
Data presented in an orderly manner
facilitate statistical analysis. There are two
different models in which the collected
data may be presented:
 Diagrams, and
 Graphs.


Analysis:

 The purpose of analyzing data is to dig
out information useful for decision –
making.
 Ex: Measures of Central tendency,
Measures of Variation, Correlation and
regressions etc…


Interpretation:
 Drawing conclusions from the data collected
and analyzed.
 The interpretation of data is difficult task
and necessitates a high degree of skill and
experience.
 If the data that have been analyzed are not
properly interpreted, the whole object of the
investigation may be defeated and fallacious
conclusion be drawn.


Functions of Statistics
 These are the important functions of
Statistics
• It presents facts in a definite form.
• It simplifies mass of figures.
• It facilitates comparison.
• It helps in formulating and testing
hypothesis.
• It helps in prediction. 13


Applications of Statistics
 Thefollowing are the important
Applications of Statistics
• Statistics and the State
• Statistics and business
• Statistics and Economics
• Physical sciences
• Natural sciences
• Statistics and Research 14


Data
 The measurements obtained in a research
study are called the data.
 The goal of statistics is to help researchers
organize and interpret the data.
 Data may be obtained either from the
primary source or the secondary source.

15


Data Contd…
A primary source is one that itself
collects the data.

A secondary source is one that makes
available data which were collected by
some other agency.

16


Methods of collecting Primary Data

 Direct personal interviews
 Indirect oral interviews
 Information from correspondents
 Mailed questionnaire method
 Schedule sent through enumerators

17


Direct Personal Interviews
 There is a face to face contact with the persons
from whom the information is to be obtained
(informants).
 First hand information or original in
character.
 Example:
 A person wants to collect data about the working conditions of
the workers of the Tata textile mill, chennai, he would go to
the mill, contact the workers and obtain the desired
information. 18


Indirect Oral Interviews
 The investigator contacts third parties called
witnesses capable of supplying the necessary
information.
 Example:
 In an enquiry regarding addiction to drugs, alcohol, etc.,
people may be reluctant to supply information about their
own habits. In that situation, this type information is collected
from their neighbours, friends etc.,
 Clues about thefts
 Murders
19


Information From Correspondents
 The investigator appoints local agents or
correspondents in different places to collect
information.
 These correspondents collect and transmit the
information to the central office where the
data are processed.
 Example:
 News paper agencies generally adopt this method.
 Correspondents in different places supply information
relating to such events as accidents, riots, strikes etc., 20


Mailed Questionnaire Method

A list of questions pertaining to the survey
(Questionnaire) is prepared and sent to the various
informants by post.
 The questionnaire contains questions and provides
space for answers.
 Request is made to the informants through a
covering letter to fill up the questionnaire and send
back within a specified time.
 Example: This method is appropriate in cases where
informants are spread over a wide area, i.e., in case of
21
extensive surveys.

Mailed Questionnaire Method Dr.R.VARADHARAJAN, MBA DEPT, VELS UNIVERSITY

Contd…
 Covering letter
 Number of Questions should be small
 Questions should be arranged logically
 Questions should be short and simple to understand
 Personal Questions should be avoided
 Instructions to the informants
 Questions should be capable of objective answer
 Yes or No Questions
 Questions should look attractive 22


Schedule Sent Through Enumerators

 The enumerators contact the informants, get replies
to the questions contained in a schedule and fill them
in their own handwriting in the questionnaire form.
 It can be adopted in those cases where informants are
illiterate.
 This method is costly among the above discussed
method.
 Some special skills are required to collect the
information from the respondents.
23


Sources of secondary data:

 Published sources

 Unpublished sources

24


Published Sources

 Reports and official publications
 Semi-official publications of various local
bodies such as municipal corporations and
district boards.
 Financial and economic journals.
 Annual report of joint stock companies and
corporations.
25


Unpublished Sources

 All statistical material is not always
published.

 There are various sources of unpublished
data such as records maintained by various
Government and Private offices, studies
made by research institutions, scholars, etc.,
such sources can be used where necessary. 26


Classification:

 Classification is the grouping of related
facts into classes.
Ex: Sorting letters in a post office.
(according to their destination like
Mumbai, Calcutta etc…)


Classification Contd…

 Types of Classification:
• Geographical (ie) Area – wise
• Chronological (ie) on the basis of time
• Quantitative (ie) in terms of magnitudes
• Qualitative (ie) according to some
attributes


Geographical Classification

 The data are classified on the basis of
geographical or vocational differences
between the various items.
 Like countries, states, cities, zones, areas,
etc.,


Country – Wise Comparison of Yield of
Rice (Metric Tones / Hectares)

Name of the Country Production of Rice
Egypt 9.87
India 8.78
USA 7.67
Japan 6.54
Korea 5.36
Myanmar 6.89
Aveaage 7.52


Chronological Classification

 When data are observed over a period of
time the type of classification is known as
chronological classification
 We may present the figures of population
as follows:


Population of India From 1951 to 2001

Year Population (In Crores)
1951 37.11
1961 43.92
1971 54.82
1981 68.33
1991 84.64
2001 102.87


Quantitative Classification

 Thedata are classified according to some
characteristics that can be measured.

 Such as height, weight, income, sales,
profits, production, etc.,


The students of a college may be classified
according to weight as follows

Weight No. of Students
40-50 50
50-60 200
60-70 250
70-80 150
80-90 60
90-100 40
Total 750


Qualitative Classification

 The data are classified on the basis of some
attribute or quality.
 Such as sex, colour of hair, literacy,
religion, etc.,
 The point to note in this type of
classification is that the attribute under
study cannot be measured.


The Population may be Classified as
follows


Tabulation:

A table is a systematic arrangement
of Statistical data in columns and
rows. Rows are horizontal
arrangements whereas columns are
vertical ones.
 The purpose of a table is to simplify
the presentation and to facilitate
comparisons.


Tabulation Contd…

 Parts of a table:
• Table number
• Title of the table
• Caption stub
• Stub
• Body
• Head notes
• Footnotes


Types of Tables

 Simple and complex tables.

 General
purpose and special
purpose tables.

39


Diagrams and Graphs
 Diagramsand graphs are extremely
useful because of the following
reasons.
• They give birds eye view of the entire
data and, therefore, the information
presented is easily understood.
• Pictorial presentation helps in proper
understanding of the data as it gives an
interesting form to it.
40


Types of Diagrams
 One – dimensional diagrams
Ex: Bar diagrams.
 Two – dimensional diagrams

Ex: Rectangles, squares and circles.
 Three – dimensional diagrams

Ex: Cubes, cylinders and spheres.
 Pictograms and cartograms
41


Bar diagram


Multiple Bar Diagram
6

5

4
Rice
3
Wheat
2 Maize

1

0
2005 2006 2007 2008


Sub Divided Bar Diagram


Percentage Bar Diagram


Line Chart


Pie Diagram


Scatter Diagram


Variables
A variable is a characteristic or
condition that can change or take on
different values.
 Most research begins with a general
question about the relationship
between two variables for a specific
group of individuals.

49


Types of Variables
 Variables can be classified as discrete or
continuous.

 Discrete variables (such as class size)
consist of indivisible categories, and
continuous variables (such as time or
weight) are infinitely divisible into
whatever units a researcher may choose.
 For example, time can be measured to the
nearest minute, second, half-second, etc.
50


Continuous variable
 Can take any value in the given
range of numbers
 Can be measured
 Ex:
• Hb level
• Height
• Weight etc

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