CASE-LEVEL DESIGN
Chapter 8
CASE-LEVEL RESEARCH
DESIGNS
• ‘Blueprints” for studying single cases
– Individual, group, organization, or community
• Also called single subject, single case, or
idiographic research
• Case-level designs symbols
– A: baseline
– B: intervention
– C, D, E: each letter is a different intervention
EXPLORATORY CASE-LEVEL
DESIGNS
• Used to explore (or learn about) if a
problem exists for a particular case and if
so, whether the problem endures with or
without intervention
A Design
• Answers the questions:
– Does a problem exist?
– Is the problem changing over time without
intervention?
• The assessment or baseline phase
• A client problem (or variable) is
operationally defined, systematically
measured on repeated occasions, and the
scores graphed
Features of case-level graphs
• Horizontal line is the x-axis (time interval)
• Vertical line is the y-axis (variable score)
– Red line is actual case score
y-Axis
• Dotted-line is the clinical cutting (normed) score
100
50
0
1
2
3
x-Axis
4
B Designs
• Answers the question:
– Is the problem changing over time while an
intervention is being applied?
• Levels of the problem are monitored at the
same time that you are applying the
intervention
• No baseline or assessment measures
were collected
BB1 Design
• B represents a specific intervention
applied to the case
• B1 indicates that the original intervention
(B) was modified in a subtle but important
way
BC Design
• B represents the first intervention applied
to the case
• C represents a second (and entirely
different) intervention applied to the case
DESCRIPTIVE CASE-LEVEL
DESIGNS
• Used to describe a case-level problem
during both the assessment and
intervention phases of the helping process
• Do not provide evidence that an
intervention “caused” any observed
change
AB Design
• Answers the question:
– Compared to baseline, does the problem
improve, worsen, or stay the same when a
single intervention is being applied?
• A tracks baseline or assessment scores
• B tracks scores during an intervention
ABC and ABCD Designs
• Answers the question:
– Compared to baseline, does the problem
improve, worsen, or stay the same when
different interventions are applied in
sequence?
• Because multiple interventions are
applied, you will not know whether change
is associated with a single intervention or
the combination of interventions
EXPLANATORY CASE-LEVEL
DESIGNS
• Answers the question:
– Is an intervention responsible for observed
changes in the case-level problem? Or Does
the intervention cause change?
• Explanatory designs eliminate other
potential causes of change to isolate the
intervention being studied
Reversal Designs
• An interventions is first applied and then
removed from the case
– If the intervention works, then the problem
should improve during intervention and return
to a problematic state when the intervention is
removed
ABA and ABAB Designs
• Answers the question:
– Does the intervention cause change in the
target problem?
• Begins with an assessment phase (no
intervention)
• Repeated withdrawals of intervention
strengthen the research design
BAB Design
• Answers the question:
– Does the removal of the intervention cause
change in the target problem?
• Begins with the intervention phase
– Useful for crisis problems
BCBC Design
• Answers the question:
– Do different interventions cause change in the
target problem? Or Which intervention
produces a more desirable outcome?
• An assessment phase is not included
Multiple Baseline Designs
• A second type of explanatory case-level
designs
• Used with
– More than one case
– (One case) with more than one setting
– (One case) with more than one problem
More than One Case
• The same case-level design is applied to
multiple cases (clients)
• “Causality” is determined by similar
patterns of improvement across different
cases that are suffering from the same
problem and exposed to the same
intervention
More than One Setting
• One case-level design is used multiple
times in different locations for a single
case (client)
• “Causality” is determined by similar
patterns of improvement across different
settings
More than One Problem
• Once case-level design is used multiple
times to monitor different problems for a
single case (client)
• “Causality” is determined by similar (or
corresponding) patterns of improvement
across different problems
SUMMARY
• Case-level research designs are used to
monitor change in a target problem over
time
• They are Ideal for tracking client change