Organisation of Data

Statistics for Grade 11 CBSE

1. ORGANISATION OF DATA
Organization of data refers to the arrangement of
figures in such a form that comparison of the mass of
similar data may be facilitated and further analysis
may be possible.
Eg. Classification of Data

2. O
Classification of Data
The process of grouping data according
to their characteristics is known as
classification of data.

3. Objectives of Classification:
a] To simplify complex data
b] To facilitate understanding
c] To facilitate comparison
d] To make analysis and interpretation easy.
e] To arrange and put the data according to their
common characteristics.

7. CHRONOLOGICAL CLASSIFICATION

14. Characteristics of a Good Classification
1.Comprehensiveness
2.Clarity
3.Homogeneity
4.Suitability
5.Stability
6.Elastic

15. Concept of Variable
A characteristic or a phenomenon which is capable of being measured
and changes its value overtime is called variable.
A) Discrete Variable
Discrete variables are those variables that increase in jumps or in
complete numbers. (No fraction is possible)
Eg. Number of students in a class, Number of cars in a show room
etc. (1,2, 10,or 15 etc.)
B) Continuous Variables
Variables that assume a range of values or increase not in jumps
but continuously or in fractions are called continuous variables.
Eg. Height of the boys –5’1’’ , 5’3’’ and so on, Marks in any range
0-10, 10-15, 15-20

16. Statistical Series
Systematic arrangement of statistical data
Raw data: Data collected in original or crude form.
Series: Arranging of raw data in different classes according
to a given order or sequence is called series.

17. Conversion of Raw Data into Series
1. Individual Series without frequency
2. Frequency series or Series with frequencies.
1] Individual Series: The arrangement of raw
data individually without
frequency

18. Individual Series can be expressed in two ways.
a] According to Serial Numbers
b] Ascending or descending order.
In ascending order, smallest number is placed first.
In descending order, the highest number is placed first.
Roll Number Marks
1 30
2 25
3 15
4 30
5 25

19. 2) Frequency Series
Two types
1. Discrete Series or Frequency Array (tally bars). No
class interval
2. Frequency Distribution (tally bars) with class
interval

20. Frequency Distribution
Frequency distribution refers to a table in which
observed values of a variable are classified according
to their numerical magnitude.
1. Discrete Series: A variable is called discrete if the
variable can take only some
particular values.
2. Continuous Series: A variable is called continuous if
it can take any value in a given
range.

21. In constructing continuous series we come across terms like:
a] Class : Each given internal is called a class e.g., 0-5, 5-10.
b] Class limit: There are two limits upper limit and lower limit.
c] Class interval: Difference between upper limit and lower limit.
d] Range: Difference between upper limit and lower limit.
e] Mid-point or Mid Value: Upper limit -Lower limit
2
f] Frequency: Number of items [observations] falling within a
particular class.

22. Exclusive Series

23. Inclusive Series

24. Open Ended Classes

25. iii] Cumulative Frequency Series:
It is obtained by successively adding the frequencies of
the values of the classes according to a certain law.
a] ‘Less than’ Cumulative Frequency Distribution :
The frequencies of each class-internal are added
successively.
b] ‘More than’ Cumulative Frequency Distribution:
The more than cumulative frequency is obtained
by finding the cumulative totals of frequencies
starting from the highest value of the variable to
the lowest value.

26. Less than frequency More than frequency
Total = 50