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

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

BB 1 Design B represents a specific intervention applied to the case B 1 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