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Was the Intervention Effective? Using Single-Case Design in the Classroom
Transcript of Was the Intervention Effective? Using Single-Case Design in the Classroom
Patricia O'Malley, Ph.D.
Kennedy Krieger Institute,
March 17, 2014
ASCD 69th ANNUAL CONFERENCE & EXHIBIT SHOW
Number of Words Correct
Individual "case" is the unit of intervention and data analysis
Use of baseline/intervention phases
The student serves as own control for purpose of comparison
Repeated measurement of DV within and across phases
Experimental control (e.g., operationally defined, fidelity, social validity)
Visual analysis to determine effect
Get out your handout.
Now let's review visual analysis and strategies for interpretation.
Outline the defining features of SCD
Highlight relevance to educational decision-making
Provide guidelines for implementation and data collection
Review visual analysis techniques
Share interpretation strategies
What are we talking about?
SCD is an experimental research design that involves repeated, systematic measurement of a dependent variable before, during, and after the use on an intervention.
The purpose is to determine a
"Was the intervention effective?"
Data are often represented visually using a time series line graph.
Current Trends in Education
Intervention was successful
The ABAB Design
As a result of legislative attention to ensure access and improvement in academic performance, the educational system has become
Focused on evidence-based practices
Two separate phases that are alternated over time.
A Phase: baseline when no intervention is in effect
B Phase: the intervention
The A and B phases are repeated again
This session will outline how single-case designs (SCD), more precisely
ABAB designs, may be incorporated into RTI to help guide educational decisions and practices to support student learning.
Kennedy Krieger School programs offer special education and related services to approximately 430 students aged 3-21 in day school settings and in partnership settings within public schools.
The array of disorders served includes:
Traumatic brain injury, and
(Students with multiple disabilities are also included.)
Services focus on the development of academic, social, emotional and behavioral skills through comprehensive instruction in an environment that recognizes the child's individual strengths.
Independent Variable (IV):
the variable that is
manipulated; the condition that is expected to bring observable change in participants
Dependent Variable (DV):
the target behavior that is measured; reflects influence of IV.
Measures group performance; Two separate groups are compared
Compare the performance
of an individual or a group to themselves (before and after a specified intervention).
Small n design
Steps to successful design:
of target, target behavior, procedures
Frequent data collection
Adequate # of data points
Criteria for demonstrating evidence of relationship between IV and DV
Document the immediacy of effect, proportion of overlap, consistency of
data across phases
Examine external factors
Document consistency of
level, trend, and
variability within each phase
If behavior is stable under “Phase A”, and if the behavior changes when “Phase B” is introduced,
then it is probably that “B” caused the change.
Three factors confirm this logic & establish a causal relationship:
- at baseline predict what will occur when intervention is applied
- return to baseline to demonstrate that level of baseline would have remained if no intervention was used
- reintroduce intervention to demonstrate that intervention has same “effect” as before
Assess within natural context
Highlight individual differences
Subjectivity of visual analysis
Examination of data within each phase:
mean or median of the data
within a phase.
ate of change;
the slope of
the best-fitting straight line for the data
within a phase.
the stability of data;
the range or standard deviation of data
about the best-fitting straight line.
Types of SCD in education research:
Interrupted Time Series
Examination of data across phases:
change in level between
data points from one phase to the next.
proportion of data from one
phase that overlaps with data from the
6. Consistency of data:
pattern of responding
in similar phases.
Other questions to ask...
Do the data confirm the problem?
What other information do the data provide?
How can the data be used to address planning and services?
Are there other factors that may be contributing to the problem?
Are there any missing data?
SCD demonstrate cause-effect relationship
Measure individual performance
Involve systematic, intensive, repeated measurement
Offer effective and efficient approach for data-based decision making about an educational intervention.