case-level design chapter 8. case-level research designs ‘blueprints” for studying single cases...
Post on 20-Dec-2015
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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
• Dotted-line is the clinical cutting (normed) score
0
50
100
1 2 3 4
x-Axis
y-Axis
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