The Characteristics of an Experimental Hypothesis
The Inductive Model
The Deductive Model
Combining Induction and Deduction
Building on Prior Research
Serendipity and the Windfall Hypothesis
Intuition
When All Else Fails
Searching the Research Literature
What is a hypothesis?
A hypothesis is an explanation of a relationship
between two or more variables.
The Characteristics of an Experimental Hypothesis
What is an experimental hypothesis?
An experimental hypothesis is a tentative
explanation of an event or a behavior. It is a
statement that predicts the effect of an
independent variable on a dependent variable.
For example, cognitive behavior therapy (CBT)
produces less relapse than antidepressants.
The Characteristics of an Experimental Hypothesis
What is an nonexperimental hypothesis?
A nonexperimental hypothesis predicts how
variables (events, traits, or behaviors) might be
correlated, but not causally related.
For example, red-haired patients receive less
relief from pain medication than blonde patients.
The Characteristics of an Experimental Hypothesis
Why must a hypothesis be a synthetic statement?
When we state a hypothesis, we then gather
data that either support or contradict it.
For this reason, a hypothesis must be capable
of being true or false, which is a property of
synthetic statements.
The Characteristics of an Experimental Hypothesis
What is testability and why is it important?
An experimental hypothesis is testable when
it can be assessed by manipulating an IV and
measuring the results on the DV.
Without testability, we cannot evaluate the
validity of a hypothesis.
The Characteristics of an Experimental Hypothesis
Why should hypotheses be parsimonious?
Parsimony means that we prefer a simple
hypothesis over one requiring many supporting
assumptions.
A simple hypothesis allows us to focus our
attention on the main factors that influence
our dependent variable.
The Characteristics of an Experimental Hypothesis
Explain the inductive model of formulating a
hypothesis.
Induction is reasoning from specific cases
to general principles to form a hypothesis.
Researchers use inductive reasoning to
construct theories by creating explanations
that account for empirical data (observations).
The Inductive Model
How can we build a theory using induction?
Scientists can use the results of extensive
experiments designed to test hypotheses to
construct a theory that unifies their findings.
The Inductive Model
Explain the deductive model of formulating a
hypothesis.
Deduction is reasoning from general principles
to specific predictions. This approach is used to
test the assumptions of a theory.
The Deductive Model
How can researchers combine induction and
deduction?
Develop propositions using induction by
examining specific cases. Then, make
predictions using deduction.
Walster et al. formulated equity theory based
on specific observations (induction) and then
tested predictions from this theory (deduction).
Combining Induction and Deduction
What is the most useful way to develop a
hypothesis?
Review research that has already been
published. Both experimental and
nonexperimental studies can prove helpful.
Building on Prior Research
How does a review of prior experiments help us
develop a hypothesis?
A review of prior experiments helps in five ways:
 Identifies questions that have not been
conclusively answered or addressed at all
 Suggests new hypotheses
 Identifies additional variables that could
mediate an effect
Building on Prior Research
How does a review of prior experiments help us
develop a hypothesis?
 Identifies problems other researchers have
experienced
 Helps avoid duplication of prior research
when replication is not intended
Building on Prior Research
How does serendipity help develop fruitful
hypotheses?
A scientist who is open to unexpected results
and who is sufficiently informed can understand
the significance of unexpected findings.
However, a dogmatic scientist would be less
likely to “see” or appreciate the significance of
serendipitous events.
Serendipity and the Windfall Hypothesis
What is intuition?
Intuition is knowing without reasoning, or
unconscious problem-solving. Intuition guides
what we choose to study in an experiment.
Intuition must be directed by our literature
review.
Intuition
What are helpful strategies for developing
experimental hypotheses?
Three promising strategies are:
(1) Read an issue of a psychology journal
(2) Observe how people behave in public places
(3) Choose a real-world problem and try to
identify its cause.
When All Else Fails
What is the purpose of the Introduction section of an
APA-format paper?
The Introduction section provides a selective
review of research findings related to the
research hypothesis.
This section identifies which questions have not
been definitively answered by previous studies
and helps show how your experiment advances
knowledge in this area.
Searching the Research Literature
Explain the value of a meta-analysis?
A meta-analysis can provide helpful information
about your topic.
A meta-analysis is not an experiment, but rather
a statistical analysis of many similar studies.
Searching the Research Literature
Explain the value of a meta-analysis?
A meta-analysis measures the average effect
size of an independent variable across studies
that share similar methodologies.
This statistical procedure helps establish
the strength and external validity of a causal
relationship.
Searching the Research Literature