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Introduction
 The word ‘Statistics’ seems to be derived from the Latin word ‘Status’
which means a ‘Political State’. Originally, statistics was simply the
collections of numerical data on some aspects of life of the people
useful to the government. However, with the passage of time, its
scope broadened. Today, Statistics means collection of facts or
information concerning almost every aspect of life of the people
with a definite purpose in the form of numerical data, organisation,
summarisation and presentation of data by tables and graphs
(charts), analysing the data and drawing inferences(meaningful
predictions) from the data.

Collection of Data
• Statistical data collection is the operation of statistical
data processing aimed at gathering of statistical data and
producing the input object data of a statistical survey.
• The first step in any enquiry (investigation) is collection
of data.
• The data may be collected for the whole population or
for a sample only.
• It is mostly collected on sample basis.

Types of Collection of Data
• Raw Data : The original data recorded in its form
as it is collected by the investigator or received
from some source is called raw data.
• Secondary Data : The information gathered from
a source which already had the information
stored is called secondary data.

Frequency Distribution Table
A tabular arrangement of
given numerical data
showing the frequency of
different variates is called
frequency distribution,
and the table itself is
called frequency
distribution table.

Group Frequency Distribution Table
A grouped frequency
distribution is the
organizing of raw data
in table form, using
classes and frequencies.

 Lower Limit:The smallest number within
the class limit.The minimum of a class
limit.To demonstrate Lower Class Limits
are in bold:
 Upper Limit: An upper class limits is the
Maximum value within a class limit.
Example of the Upper Class Limits or
Maximum Class limit are bold:

Graphical Representation of Data
• A graphical representation is a visual display of data and
statistical results. It is often more effective than
presenting data in tabular form. There are many different
types of graphical representation and which is used
depends on the nature of the data and the type of
statistical results.

Bar Graph
• A bar graph is a chart that uses bars to show comparisons between
categories of data. The bars can be either horizontal or vertical.

Histogram
• A histogram is a graphical representation of the distribution of
numerical data.

Frequency Polygon
• In a Frequency Polygon, a line graph is drawn by joining all the
midpoints of the top of the bars of a histogram.

CLASS MARK
 The number in the middle of the class. It is found by adding the upper and lower limits
and dividing by two. It can also be found by adding the upper and lower boundaries and
dividing by two.

MEASUREMENT OF CENTRALTENDENCY
A measure of
central tendency
is a measure that
tells us where
the middle of a
bunch of data
lies.

MEAN
 The mean is the average of the numbers: a calculated "central"
value of a set of numbers.

MEDIAN
 The median is defined as the number in the middle of a given set
of numbers arranged in order of increasing magnitude.

MODE
 The mode is defined as the element that appears most frequently in a
given set of elements.

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