Quantitative Research Methodology

1
Quantitative Research Methodology

• Session 2
• Variables, Population, and Sampling

2
Variable

• 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)

3
Variable (2)

• 2. Dependent Variable
• a response variable or output (Tuckman, 1999,
  p. 93)

4
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 studys primary independent variable and it
  dependent variable (Tuckman, 1999, p. 97).

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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)

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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)

7
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).

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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.

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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.

10
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).

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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

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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

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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)

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Examples

• 4. Hypothesis
• Among lower class-children, tangible
  reinforcement conditions will produce
  significantly more learning than intangible
  reinforcement conditions

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Examples

• 5. Hypothesis
• Teachers given many positive feedback
  experiences will have more positive attitudes
  toward children than teachers given fewer
  positive feedback experiences.

16
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)
• Target Population
• A subset of the population
• Parameter
• Numerical measures of a population
• Statistic
• Numerical measures of a sample

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Sampling

• Probability Sampling (Random Sampling)
• Nonprobability Sampling (Nonrandom Sampling

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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)

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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.

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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