Download topic 8.0 : data descriptive

8.1 INTRODUCTION OF DATA
8.2 FREQUENCY DISTRIBUTIONS
8.3 MEASURES OF LOCATION
8.4 MEASURES OF DISPERSION
SUBTOPIC 8.1 :
Introduction of Data
OBJECTIVES
(a) Clarify the meaning and the use of
statistics
(b) Define the basic terms; population,
parameter, sample, statistic and
variables.
(c) Define quantitative and qualitative
(d) Define the discrete and continuous data
(e) Clarify ungrouped and grouped data
SET INDUCTION
These are Mathematics marks for 30
students who are taking mid-semester test
12 , 23, 24, 45, 34, 48, 56, 63, 23, 44,
69, 78, 84, 95, 98, 67, 73, 69, 58, 70,
40, 88, 59, 47, 37, 15, 17, 36, 63, 38
How to interpret these marks?
WHAT IS STATISTICS ?
~ Is the science that deals with
collecting, classifying, presenting,
describing, analyzing and interpreting
data to enable us to draw conclusions
and making reasonable decisions
~ Divided into 2 categories
(a)
Descriptive statistics
(b) Inferential statistics
Descriptive statistics
~
The activities of collecting,
classifying, presenting and describing
quantitative data
Inferential statistics
~
The part dealing with technique
and method of interpretation of the
results obtained from the descriptive
statistics
WHAT IS POPULATION ?
~
Is the entire (complete) collection
of data whose properties are analyzed.
It contains all the subjects of interest.
~
Can be of any size, its items need
not be uniform but must share at least
one measurable feature.
WHAT IS SAMPLE?
~
A portion of population selected
for study
~
Is any set of entities, cases,
subjects, items or experimental
units chosen from the population.
Population
Sample
Eg: To study the heights of students in KMPP
WHAT IS RANDOM SAMPLE?
~
A random sample is a sample
selected in such a way that each
element of the population has the
same chance of being selected
WHAT IS PARAMETER ?
~
Is a numerical measurement
describing some characteristics of
a population
2

~

Eg: The population mean , variance
WHAT IS statistic?
~
~
Is a numerical measurement
describing some characteristics of
a sample
2
x
S
Eg: The sample mean ,variance
WHAT IS VARIABLES ?
~
Any measured characteristic or
attribute that differs for different
elements
~
For example, if the weight of 30
subjects were measured, then
weight would be a variable.
~
Can be classified as quantitative or
qualitative
WHAT IS quantitative
VARIABLES ?
~
The variable being studied is
numeric
~
measured on an ordinal, interval,
or ratio scale
~
eg: If the time it took them to
respond were measured, then the
variable would be quantitative.
WHAT IS qualitative
VARIABLES ?
~ The variable being studied is non-numeric
~ Called "categorical variables”
~ Measured on a nominal scale
~ eg: gender, educational level, eye
colour
If five-year old students were asked to
name their favourite colour, then the
variable would be qualitative.
WHAT IS DATA ?
~
A set of data is a collection of
observation, measurements or
information obtained
~
Can be classified as quantitative or
qualitative
~
Can be presented in various way
WHAT IS quantitative DATA ?
~
Quantitative data refers to
observations which can be
measured numerically or counted
~
Can be divided into discrete data
and continuous data
~
eg:
length, time,
temperature and mass
WHAT IS qualitative DATA ?
~
Qualitative data are not in
numerical form but instead
assigned as attributes
~
eg:
race, marital status, age, sex
Discrete data
~
Is a data that can only take exact
and countable values
~
For example:
a)
b)
c)
d)
The number of students in a class.
The number of cars sold on any day
at a car dealership.
Number of persons in a family.
Number of students in a class.
Continuous data
~
Is a data can take any value over
certain interval and can be measured
to a certain degree of accuracy
(correct to certain decimal places)
~
For example:
a)
The weight of students in a class.
b)
The time taken to complete an
examination.
c)
The amount of soda in a 150ml can.
d)
Income of a family.
WHAT IS UNGROUPED DATA ?
~
(a) Raw data
(b) Not in the term of interval
(c) Frequency distribution that has
been arranged in order
~
Example:
(i) 3,5,6,2,5,2,4,6,5
(ii)
Number of books
Frequency
0
3
1
7
2
4
3
2
WHAT IS GROUPED DATA ?
~
The data can be grouped into class
interval before the frequency
distribution is constructed
~
The table constructed is called
frequency distribution table
~
Example:
Height
150-155 155-160 160-165 165-170
(cm)
Frequency
2
8
6
5
Examples:
Determine whether the data obtained
is discrete or continuous data.
(a) The number of books sold by
Discrete
stationary shop.
(b) The time taken to travel from Kuala
Terengganu to Batu Pahat
Continuous
(c) The numbers of A’s for UPS in this
session
Discrete
(d) The weight of the students in a
practicum
Continuous
(e) The diameter of twenty spheres Continuous
REMARKS…
• All data are to be considered as sample
unless otherwise stated in the
questions.