1. Stuti Ranjan
XI-D

2. “Statistics is the science that deals with the
method of collecting, classifying,
presenting, comparing ,and interpreting
numerical data collected to throw some
light on any sphere of enquiry.”
-Seligman

3. Collection
of data
Organisatio
n of data
Presentation
of data
Analysis
of data
Interpretatio
n of data
Stage 1 Stage 2 Stage 3 Stage 4
Stage 5

4. Each stage of statistical study involves the use
of certain techniques or methods
Stages Statistical study Statistical tools
Stage 1 Collection of data Census or
sample method
Stage 2 Organisation of
data
Tally bars
Stage 3 Presentation of
data
Tables, graphs
and polygons,
histograms etc
Stage 4 Analysis of data Percentages
,Averages
Stage 5 Interpretation of
data
Magnitude of
percentages

5.  Graphic representation gives a visual effect.
Its used in research work for visual
presentation and analysis of data. The
graphic method enables us to present data in
a simple, clear and effective manner
 There are many varieties of graphs .Broadly
graphs can be divided into two parts:
a) Graphs of frequency distribution
b) Graphs of time series

6.  Histogram is joining rectangular diagram of a continuous
series in which each rectangle represents the class interval
with the frequency .It is a two-dimensional diagram and also
called frequency histogram.
Cases of constructing a hisogram
i. Histogram of equal class interval
ii. Histogram when mid points are give
iii. Histogram when unequal class intervals

8. Scores(mid
points)
Frequency
5
15
25
35
45
2
5
7
10
4
Ascertainment of lower and upper
limits :
Get the difference between the first
and the second mid point .
Divide it by 2 to get the intervals and
then draw the histogram.

9. Before presenting the data in the form of
graphs and frequencies , unequal class
intervals are adjusted.
Adjustment factor=class interval of
concerned class divided by lowest class
interval
Marks No of
students
Adjustment
factor
Frequency
density
30-50
50-60
60-70
70-90
90-100
48
30
20
28
16
20/10=2
10/10=1
10/10=1
20/10=2
10/10=1
48/2=24
30/1=30
20/1=20
28/2=14
16/1=16

10.  Polygon is another form of diagrammatic presentation
of data .
 It is formed by joining all the mid points of the tops of
all rectangles .however they can be formed even
without constructing a histogram.
 Frequency polygons can be drawn in two ways:
i. With a histogram
ii. Without a histogram

11. Class limits No of sareees
100-200
200-300
300-400
400-500
500-600
600-700
700-800
10
27
37
24
20
15
10
The total area excluded from the
histogram is equal to the area
included under frequency polygon

12. Mid points Frequency
55
65
75
85
95
1
4
6
5
2

13. THANK YOU