Details overview

1. Presentation
of data

2. Classification
The process of dividing a set of observations or objects
into classes or categories according to similar categories.
One way classification(data is sorted according to 1
criterion)
Two way classification(data is sorted according to 2
criteria)
Manifold classification(data is sorted according to several
criteria)

3. Tabulation
A systematic presentation of data classified
under suitable heads and subheads, and placed
in rows and columns.

4. Frequency distribution
The tabular arrangement of data that shows the
observations among different classes.
The number of observations in each class or
group is called class frequency.
The data presented in the form of frequency
distribution is called grouped data while the data
in the original form is called ungrouped data.

5. Class limits
The class limits are defined as the numbers or the
values of the variables which describe the
classes.
The smaller number is the lower class limit and
the larger number is the upper class limit.
e.g 10-14, 15-19, 20-24 etc.

6. Class boundaries
The class boundaries are the precise numbers
which separate one class from another.
The upper class boundary of a class coincides
with the lower class boundary of the next class.
e.g 9.5-14.5, 14.5-19.5, 19.5-24.5

7. Class mark
A number which divides each class into two
equal parts.it is also called as midpoint.
It is obtained by dividing either the sum of lower
and upper limits of a class, or the sum of the
lower and upper boundaries of the class by 2.

8. Class interval or class
width
The class interval or class width is equal to the
difference between the class boundaries. It may
also be obtained by finding the difference either
between two successive lower class limits or
between two successive class marks.

9. Frequency distribution
Class limits Frequency Midpoint(X) Class boundaries
65-84 9 74.5 64.5-84.5
85-104 10 94.5 84.5-104.5
105-124 17 114.5 104.5-124.5

11. Bar Charts: show counts or
relative frequency for each
category
Titanic Passengers by Class
885
325
285
706
0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
800.00
900.00
1000.00
Crew First Second Third
• Example: Titanic passenger/crew distribution

12. Multiple bar chart

13. Subdivided bar chart

14. Pie Charts: shows proportions of
the whole in each category
Example: Titanic passenger/crew distribution