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

• 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

SUMMARY

• Case-level research designs are used to monitor change in a target problem over time

• They are Ideal for tracking client change