Numbers or measurements that are
collected as a result of observations.
An array is a systematic arrangement of
objects, usually in rows and columns.
Data Array: Observations that are
TYPES OF DATA
There are mainly four types of
Primary statistical data
Secondary statistical data
Qualitative statistical data
Quantitative statistical data.
POPULATION VS SAMPLE
statistics includes all
members of a
defined group that
we are studying or
on for data driven
The sample is a
proportion of the
population, a slice of
it, a part of it and all
UNGROUPED VS GROUPED
It is the data
that you first gather.
Ungrouped data is
data in the raw.
It is data that
has been organized
into groups known as
data has been
'classified' and thus
some level of data
analysis has taken
place, which means
that the data is no
It is the number of observations
following in some class.
It is a listing of classes and their
There is no thumb rule about the number of
classes, but roughly it is suggested that the
number of classes should be between 8 to
Inclusive Classification: It is used for the
classes like 55-57, 58-60, ……, 68-70. Both
end points of the classes are included in the
Exclusive Classification: It is used for
the classes like 10-20, 20-30,……50-60.
The 2nd end point is not included in the
Such classes should be avoided.
The gap between the classes is
known as “height” an is denoted by “h”
The gap between class boundaries is
known as class interval.
By listing the actual observations
By using a tally column