Download Quantitative Research Methodology

Quantitative
Research
Methodology
Session 2
Variables, Population, and
Sampling
Variable
1.
A characteristic that varies
Independent Variable
“the factor that is measured,
manipulated, or selected by the
experimenter to determine its
relationship with an observed
phenomenon” (Tuckman, 1999,
p.93)
Variable (2)
2. Dependent Variable
“a response variable or output” (Tuckman,
1999, p. 93)
Variable (3)
3. Moderator Variable
“a special type of independent variable, a
secondary independent variable selected
to determine if it affects the relationship
between the study’s primary independent
variable and it dependent variable”
(Tuckman, 1999, p. 97).
Variable (4)
4. Control Variables
“Factors controlled by the
experimenter to cancel out or
neutralized any effect they might
have on observed
phenomena”(Tuckman, 1999, p.
100)
Variable (5)
5. Intervening Variable
“a factor that theoretically affects observed
phenomena but cannot be seen,
measured, or manipulated; its effect must
be inferred from the effects of the
independent and moderator variable on
the observed phenomenon” (Tuckman,
1999, p. 101)
Hypotheses
“a prediction of the possible outcomes
of a study”(Fraenkel & Wallen, 2007,
p. 46).
“a statement about what we expect to
happen in a study” (Mackey and
Gass, 2005, p. 100).
Null and Alternative Hypotheses

Null Hypothesis (H0)
“a neutral statement used as a basis for
testing” (Mackey and Gass, 2005, p. 101).
The null hypothesis states that there are
no relationships among variables of
interests or no differences among groups
in a certain outcome.
Null and Alternative Hypotheses
 Alternative
Hypothesis (H1 or Ha)
The opposite of what is stated the
null hypothesis.
 The
research hypothesis should be
expressed as the alternative
hypothesis.
Directional and NonDirectional
Hypotheses
“A directional hypothesis indicates the
specific direction (such as higher, lower,
more, or less) that a researcher expect to
emerge in a relationship” (Fraenkel and
Wallen, 2005, p.48).
 “A nondirectional hypothesis does not
make a specific prediction about what
direction of the outcome of a study will
take” (Fraenkel and Wallen, 2005, p.48).

Examples
1.
Research Question:
Do high-proficiency learners use more language learning
strategies than low-proficiency learners?
(Wharton, 2000 in Larson-Hall, 2010, p.39)
Ho: High-proficiency learners do not use more language
learning strategies than low-proficiency learners.
Ha: High-proficiency learners use more language learning
strategies than low-proficiency learners.
Dependent Variable:
Independent Variable:
Examples
2. Hypothesis:
Anxiety affects test performance, but the
correlation is markedly lower for students
with test-taking experience.
(Fraenkel & Wallen, 2005, p.44)
Dependent variable:
Independent variable:
Moderator variable:
Examples
3. Hypothesis:
High school students taught primarily by
the inquiry method will perform better on
tests of critical thinking than will high
school students taught primarily by
demonstration method, although the
reverse will be true for elementary school
students.
(Fraenkel & Wallen, 2005, p.44)
Examples
4. Hypothesis:
Among lower class-children, tangible
reinforcement conditions will produce
significantly more learning than
intangible reinforcement conditions
Examples
5. Hypothesis:
Teachers given many positive
feedback experiences will have more
positive attitudes toward children
than teachers given fewer positive
feedback experiences.
Population and Sample
The entire elements of interest in a particular
study
 Target Population
“The actual population to which a researcher
really to generalize…” (Fraenkel & Wallen, 2005,
p.93)
 Accessible Population
“The population to which a researcher is able to
generalize…”
(Fraenkel & Wallen, 2005, p.93)
Sampling
 Probability
Sampling (Random
Sampling)
 Nonprobability Sampling
(Nonrandom Sampling
Random Sampling Methods
Simple Random Sampling
“Every member of the population has an equal
and independent chance of being selected”
(Fraenkel & Wallen, 2007, p. 95)

Stratified Random Sampling
“A process in which certain subgroups, or strata,
are selected for the sample in the same
proportion as they exist in the population
“(Fraenkel & Wallen, 2007, p. 96)

Random Sampling
 Cluster
Random Sampling
Every groups in the population has
the same probability of being
selected
 Two-Stage Random Sampling
A combination of cluster random
sampling and individual random
sampling.
Nonrandom Sampling Method

Systematic Sampling
“Every nth individual in the population list is selected for
inclusion in the sample” (Fraenkel & Wallen, 2007, p. 98)

Convenience Sampling
“A group of individuals who (conveniently) are available for
study” (Fraenkel & Wallen, 2007, p. 100)

Purposive Sampling
Selection of sample based on judgment of researchers