VARIABLES
Variable Defined:
It is a property or
quantity that can
take on different
values.
Example:
Effect of Light and
Temperature on the
Growth of Plants
Kinds of Variables
Independent Variable
Dependent Variable
Independent Variable
It is the variable that is varied or
manipulated by the researcher.
An independent variable is
the presumed cause
Dependent Variable
It is the response that is
measured.
A dependent variable is the
presumed effect.
Example 1
You are interested in “How stress
affects mental state of human
beings?”
Independent variable - stress
Dependent variable - mental
state of human beings
Example 2
Promotion affects employees’
motivation
Independent variable promotion
Dependent variable employees’ motivation
Example 3
“Predictors of Students’ Performance
in Chemistry Laboratory of Selected
Private Schools”
Independent variable - Chemistry
Laboratory Activities
Dependent variable - Students’
Performance
A group of high school students were
given a short course in speed-reading.
The teacher was curious if a monetary
incentive would influence
performance on a reading test taken
at the end of the course. Half the
students were offered P50 for
obtaining a certain level of
performance on the test, the other
half were not offered money.
Does heating a cup
of water allow it to
dissolve more
sugar?
Does fertilizer
make a plant
grow bigger?
Does an electric
motor turn faster if
you increase the
voltage?
How fast does a
candle burn?
Is a classroom
noisier when the
teacher leaves the
room?
How much water
flows through a
faucet at different
openings?
Extraneous Variables
Extraneous Variables are undesirable
variables that influence the relationship
between the variables that an
experimenter is examining. These are
variables that influence the outcome of
an experiment, though they are not the
variables that are actually of interest.
Example
An educational psychologist has developed a new
learning strategy and is interested in examining the
effectiveness of this strategy.
The experimenter randomly assigns students into
two groups. All of the students study text materials
on a biology topic for thirty minutes. One group
uses the new strategy and the other uses a strategy
of their choice.
Then all students complete a test over the materials.
Extraneous variable - pre-knowledge of the
biology topic
Does fertilizer
make a plant
grow bigger?
Continuous Variables
Are those that
take fractional
values
Discrete Variables
Are those that
assume fixed or
exact amounts
Which of these are continuous?
Which of these are discrete?
• The number of Toyota • The length of travel
cars sold by a car dealer
time
from
in one year
Tuguegarao
to
• The number of students
Manila
protesting the tuition
• The depth of drilling
increase last semester
to find oil reserves
• The number of teacher
applicants for the T3 • The amount of soda
position
in a 20-ounce bottle
Continuous or Discrete
1. Number of students engaged in sports
2. Memory capacity of a computer
3. Body temperature
4. Ages of fourth year students
5. Number of teachers in Pamplona Institute
6. Grade in Mathematics
7. Number of books in the shelf
8. Time consumed in taking a math exam
9. Distance traveled by a car
10.Dale’s height
Experimental Variables
Are those which are
subjected to a
certain treatment
(with treatment)
Control Variables
Are those which are
exposed to the absence
of the treatment
(without treatment)
NOTE:
• The same conditions hold for
the two groups
• The response to the
treatment they received are
compared to evaluate the
effect of the IV
A group of high school students were
given a short course in speed-reading.
The teacher was curious if a monetary
incentive would influence
performance on a reading test taken
at the end of the course. Half the
students were offered P50 for
obtaining a certain level of
performance on the test, the other
half were not offered money.
A farmer put organic
fertilizer to the first row
of his squash plants, but
did not place any on the
second row.
• In the study of corn husk as antihypertensive
alternative,
students who conducted the
experiment injected the solution
to 10 mice. On the other hand,
another 10 mice were left
without any corn husk treatment.
Enhancing Students’
Performance in
Graphing Functions
through Flipped
Teaching Method
Quantitative Variables
Take on values that
correspond to the
points on a real line
scale
Qualitative Variables
Take on values
that are names
or labels
A deck of cards contains both
quantitative and qualitative
variables.
• What
are
variables?
• What are
variables?
the
the
qualitative
quantitative
• The quantitative variables are the
number on the card
• The qualitative variables are the
suits (spade, clubs, heart,
diamond)
Qualitative or Quantitative
1. Gender
2. Age
3. Number of Family
Members
4. General Weighted
Average in High School
5. Type of School
Levels of Measurement
• The nominal level of measurement is
characterized by data that consist of
names, labels, or categories only.
• The ordinal level of measurement
involves data that may be arranged in
some order but differences between data
values either cannot be determined or are
meaningless.
Levels of Measurement
• The interval level of measurement is
like the ordinal level, but meaningful
amounts of differences can be determined.
It has no inherent (natural) zero starting
point.
• The ratio level of measurement is the
interval level modified to include the
inherent zero starting point.
Identify the level of measurement for each of
the following data.
1. Blood type of a patient admitted to a hospital
2. Intelligence Quotient of a student
3. Tax identification number (TIN) of an
employee
4. A student’s academic rank in high school
5. Average daily sales of a bakeshop
6. TV network
7. Most popular movie actor
8. Birth order in the family
9. Body temperature
10. Memory capacity of a computer