Chapter 5
Specifying a Purpose and Research
Questions or Hypotheses
Power Point Slides by Ronald J. Shope in collaboration with John W. Creswell
Key Ideas
• The difference between purpose
statements, hypotheses, and research
questions
• Variables in quantitative research
• Quantitative purpose statements,
questions, hypotheses
• Qualitative purpose statements,
questions, hypotheses
Educational Research 2e: Creswell
What are Purpose Statements, Research
Questions, Hypotheses, and Objectives?
Purpose Research
Research
Hypotheses
Statement Questions
Objectives
Intent
Form
Use
Placement
Overall
Direction
Raise questions
to be answered
Make predictions
about expectations
One or more
One or more
sentences
questions
One or more
questions
One or More
Objectives
Quantitative
Research
Typically
Quantitative
Research
Quantitative
and
Qualitative
Research
End of
Introduction
Quantitative
and
Qualitative
Research
State Goals
End of the introduction, after the literature
review, or in a separate section of the study
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Why are these statements
and questions important?
• Represent major signposts
• Help identify appropriate methods
• Help link intent with the results
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What We Need to Know to Design Quantitative
Purpose Statements, Research Questions, and
Hypotheses
• What is a variable?
• What is a theory?
• What elements go into these statements
and questions?
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What is a Variable?
A Variable
(A Characteristic or Attribute)
That can be
Measured
(Can be assessed
on an instrument
and recorded on
an instrument)
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and
Varies
(Can assume
different values or
scores for
different
individuals)
Examples of variables and
non-variables
Difficult but
possibly
measurable
variables
Variables
• Leadership style
• Organizational
control
• Autism
•
•
•
•
Socialization
Imagination
Intuition
Discrimination
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Almost
impossible
to measure
variables
• Subconscious
thoughts
• World poverty
• Stereotypes
Categorical and Continuous
measures of variables
• A categorical measure is a value of a
variable assigned by the researcher into a
small number of categories. (e.g. Gender)
• A continuous measure is the value of a
variable assigned by the researcher to a
point along a continuum of scores, from
low to high. (e.g. Age)
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Variables and Constructs
• A Variable is an attribute or characteristic
stated in a specific or applied way
• A Construct is an attribute or
characteristic expressed in an abstract,
general way.
Construct
Student Achievement
Variable
Grade Point Average
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The Family of Variables in
Quantitative Studies
Probable
Cause
(X)
Independent
Variables
•Treatment
•Measured
(Y)
Intervening
Variables
Effect
(Z)
Dependent
Variables
Control
Variables
Moderating
Variables
Confounding
Variables
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Families of Variables
• Dependent Variables: An attribute or
characteristic influenced by the
independent variable.
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Families of Variables
• Independent Variable: An attribute or
characteristic that influences or effects
an outcome or dependent variable.
– Treatment Variable
– Measured Variable
– Control Variable
– Moderating Variable
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Intervening Variables
• Intervening Variables (Mediating
Variables): An attribute or
characteristic that “stands between” the
dependent and independent variables.
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Example of an Intervening
Variable
Step 1
Independent
Variable
Dependent
Variable
Example Convenient office hours
Student seeks help
from faculty
for students
Step 2
Example
Step 3
Example
Independent
Independent
Variable
Variable
Convenient office hours
for students
Independent
Variable
Convenient office hours
for students
Intervening
Variable
Student becomes willing
to take risks
Intervening
Variable
Student becomes willing
to take risks
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Dependent
Variable
Student seeks help
from faculty
Families of Variables
• Confounding Variables (Spurious
Variables): Attributes or characteristics
that the researcher cannot directly
measure because their effects cannot
be easily separated from the other
variables, even though they may
influence the relationship between the
independent and the dependent
variable.
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Theories as Bridges Between
Independent and Dependent Variables
Independent
Variables
Dependent
Variables
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Different Types of Explanations in
quantitative research
Broad
Abstractions
Extensive Tests by
other researchers
As a formal theory that is expressed by connected
hypotheses and variables identified by authors
As a conceptual framework often expressed as a
visual model by other authors for relationship
As a theoretical rationale posed by other authors
based on studies for relationship
No Test
As explanation posed by the author as a hunch for
why the independent variable relates to the
dependent variable
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Narrow
Application
Elements of quantitative
purpose statement
•
•
•
•
Single sentence
“The purpose of this study . . .”
Theory
Quantitative words (e.g. “Relate,”
“Compare,” “Describe”)
Educational Research 2e: Creswell
Elements of quantitative
purpose statement
• Variables
– Independent Variable (1st position in
sentence)
– Dependent Variable (2nd position in
sentence)
– Control and/or mediating variable (3rd
position in sentence)
– Research site
– Participants
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Quantitative Research
Questions
• 3 types:
– Describe results to your variables
– Compare two or more groups on the
independent variable in terms of the
dependent variable
– Relate two or more variables
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Research Hypotheses
• Three types:
– Null hypothesis
– Directional alternative hypothesis
– Non-directional alternative hypothesis
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How do You Design Qualitative Purpose
Statements and Research Questions?
• Understand how these statements and
questions differ from quantitative
research
• Understand the role of a central
phenomenon in qualitative research
• Understand qualitative research as an
emerging process
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Differences between quantitative and qualitative
purpose statements and research questions
Quantitative - more closed
1. Probable Cause/Effect
(“Why did it happen?”)
2. Use of theories (Why did it
happen in view of an
explanation or theory?”)
3. Assessing differences and
magnitude
“How much happened?”
“How many times did it
happen?”
“What were the differences
among groups in what
happened?”
Qualitative - more open-ended
1. Descriptive (“What
happened?”)
2. Interpretive (“What was the
meaning to people of what
happened?”)
3. Process-oriented (“What
happened over time?”)
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Explaining or predicting variables versus
exploring or understanding a Central
Phenomenon
Qualitative
Understanding or
exploring a Central
Phenomenon
Quantitative
Explaining or
Predicting Variables
X
Y
The independent variable (X)
influences a dependent
variable (Y)
Y
In-depth understanding of Y;
external forces shape and are
shaped by Y
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Two qualitative research
considerations
• The focus of the research is around a
Central Phenomenon which is an issue or
a process the researcher would like to
study.
• Qualitative research is built on an
emerging design
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Elements of qualitative
purpose statement
•
•
•
•
•
Single sentence
“The purpose of this study . . . ”
Central Phenomenon
State qualitative type of design
Qualitative words (e.g. “explore,”
“understand,” “discover”)
• Participants
• Research site
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Two Types of qualitative
Research Questions:
• Central question
• Sub-questions
• Differences between research questions
and questions asked during data
collection
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