Transcript CAUSAL-COMPARATIVE RESEARCH

CAUSAL-COMPARATIVE
RESEARCH
By: Brita Groves
OBJECTIVES
• Explain what is meant by the term “causal-comparative
research.”
• Describe how causal-comparative research is both similar to
and different from both correlational and experimental
research.
• Identify and describe the steps involved in conducting a
causal-comparative study.
• Look at a diagram of a design for a causal-comparative
study.
• Describe some of the threats to internal validity that exist in
causal-comparative studies and discuss how to control for
these threats.
• Recognize a causal-comparative study when you come
across one in the educational research literature.
What is causalcomparative research?
• Also known as “ex post facto”
research. (Latin for “after the fact”).
• In this type of research investigators
attempt to determine the cause or
consequences of differences that
already exist between or among
groups of individuals.
In other words…
• Causal-comparative research is an
attempt to identify a causative
relationship between an independent
variable and a dependent variable.
• The relationship between the
independent variable and dependent
variable is usually a suggested
relationship (not proven) because you
(the researcher) do not have complete
control over the independent variable.
You are a first year agricultural education teacher at the
local high school. At the state CDE contest you run into a
Billy Bob (a fellow agricultural education teacher). When
Billy asks how your year is going, you tell them that you are
discouraged because your students do not seem to like your
teaching very much and complain about your style of
testing.
Billy Bob tells you that they have been using e-moments
and some of the concepts from the FFA Life Knowledge
materials to teach their classes. They think that their
students really enjoy their teaching and are learning more
because of it.
You wonder if Billy Bob’s approach would work for you…
• An appropriate way to approach this
situation would be with a causalcomparative study.
• You (the researcher) observe that 2 groups
differ on some variable (teaching style) and
then attempt to find the reason for (or the
results of) this difference.
***Note that the difference has already occurred.***
The Three Types
• There are 3 types of causalcomparative research:
• Exploration of Effects
• Exploration of Causes
• Exploration of Consequences
Similarities to
correlational research
• Both types of research are examples
of associational research:
• Researchers seek to explore relationships
among variables.
• Both attempt to explain phenomena
of interest.
• Both seek to identify variables that
are worthy of later exploration
• Often provide guidance for later experimental
studies.
Similarities to
correlational research
• Neither allow the researcher to
manipulate the variables.
• Both attempt to explore
causation.
Differences
Causal-Comparative
• Typically compare 2 or
more groups of subjects
• Involves at least 1
categorical variable.
• Analyzes data by
comparing averages or
uses crossbreak tables.
Correlational
• Requires a score on
each variable for each
subject.
• Investigate 2 or more
quantitative variables.
• Analyzes data by using
scatterplots and/or
correlation coefficients.
Similarities to
experimental research
• Both require at least one
categorical variable.
• Both compare group
performances to determine
relationships.
Differences
Causal-comparative
• No manipulation of the
variables.
Experimental
• The independent variable
is manipulated.
• Provide weaker evidence
for causation.
• Provide stronger
evidence for causation.
• The groups are already
formed, the researcher
must find them.
• The researcher can
sometimes assign
subjects to treatment
groups.
The steps…
• Problem Formulation
• Select the sample of individuals
to be studied.
• Instrumentation- achievement
tests, questionnaires,
interviews, observational
devices, attitudinal
measures…there are no limits…
The design
• The basic design is to select a
group that has the independent
variable and select another
group of subjects that does not
have the independent variable.
• The 2 groups are then
compared on the dependent
variable.
Internal Validity
• Usually 2 weaknesses in the
research:
• Lack of randomization
• Inability to manipulate an independent
variable
• Threats
•
•
•
•
Oftentimes subject bias occurs
Location
Instrumentation
Loss of subjects
Data Analysis
• Construct frequency polygons.
• Means and standard deviations
(only if variables are
quantitative)
• T-test for differences between
means.
• Analysis of covariance
Proceed with caution!!!
• The researcher must remember
that demonstrating a
relationship between 2
variables (even a very strong
relationship) does not “prove”
that one variable actually
causes the other to change in a
causal-comparative study.
Limitations of Use
• There must be a “pre-existing”
independent variable
• Years of study, gender, age, etc.
• There must be active variablesvariables which the research
can manipulate
• The length and number of study
sessions, instructional techniques,
etc.
Examples
• Exploration of effects caused by
membership in a given group.
• Question: What differences in
abilities are caused by gender?
• Hypothesis: Females have a
greater amount of linguistic ability
than males.
Examples
• Exploration of causes of group
membership.
• Question: What causes individuals
to join a gang?
• Hypothesis: Individuals who are
members of gangs have more
aggressive personalities than
individuals who are not members
of gangs.
Examples
• Exploration of the consequences of
an intervention.
• Question: How do students taught by the
inquiry method react to propaganda?
• Hypothesis: Students who were taught
by the inquiry method are more critical
of propaganda than are those who were
taught by the lecture method.
Example
• A Comparison of Urban Teacher
Characteristics for Student
Interns Placed in Different
Urban School Settings
• Classroom Behavior of Good
and Poor Readers
Chapter in Book
• Chapter 16
• Pages 369 to 395
• Summary on pages 393 to 394
References
• Fraenkel, J. (2006). How to design and evaluate
research in education. (pp. 369-395). New York,
NY: McGraw-Hill.
• McKinney, S. (2004). A comparison of urban teacher
characteristics for student interns placed in
different urban school settings. The
professional educator, 26(2).
• Wasson, B. (2001). Classroom behavior of good and
poor readers. The professional educator, 23(3).
• www.mnstate.edu/wasson/ed603/ed603lesson12.ht
m
• www.faculty-staff.ou.edu/B/Nancy.H.Barry1/cause.html