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Lecture   8   single subject designs i
 

Lecture 8 single subject designs i

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    Lecture   8   single subject designs i Lecture 8 single subject designs i Presentation Transcript

    • #8 Location In The Research Process Formulating Research Questions Previous Research Craft Knowledge Appropriate Design Appropriate Sampling Decisions Ensure Research Ethics Data Collection & Management Data Analysis Interpretation Dissemination Ongoing Research
    • Basic Requirements Of All Single Subject Designs
      • Continuous Assessment
        • Several observations of the target behavior
        • Across all phases of the study
        • A minimum of three times during each phase
      • Baseline Assessment Of Functioning
        • Data about what expected performance would be
        • Descriptive function (control phase)
        • Predictive function
      • Baseline Data Should Be Stable
        • Without trend and have little variability
    • Internal and External Validity
      • Internal Validity
        • The extent to which alternate explanations, beyond the variable of interest, can be ruled out
      • External Validity
        • The extent to which results of an experiment can be generalized beyond the conditions of an experiment
    • Internal and External Validity
      • Internal validity addressed through
        • Withdrawal or reversal with repeating phases
        • Comparing across multiple baselines
      • External validity addressed through replication
        • At least four cases per study
    • Two Types of Experimental Single Subject Designs
      • AB designs are pre-experimental
        • Establishing measurement accuracy
        • Detecting preliminary data trends
        • Cannot infer causality
      • ABAB Designs
        • Are Experimental
        • Withdrawal and Reversal take place
      • Multiple Baseline Designs
        • Are Experimental
        • Target behavior changes when and only when an intervention is applied to that behavior
      • A first baseline phase describes and predicts the target
      • First intervention phase, when the intervention is applied and the target is measured
      • Next comes a second baseline phase, also known as a withdrawal phase, when the intervention is removed and the target is measured
      • Finishes with a second intervention phase, maintained as long as is needed, and then faded out
      ABAB Design - Implementing
      • A stable first baseline phase
      • a marked change during the first intervention phase
      • A clear return to first baseline performance levels during the second baseline phase
      • Another marked change in the target during the second intervention phase
      ABAB Design - Analyzing
    • ABAB Design - Analyzing
      • Phases can be ordered differently within ABAB designs
        • As long as there are at least two intervention phases and two baseline phases
        • Intervention and baseline phases are adjacent to each other
      • Treatment comparisons can be made
        • An ABCABC design for example
        • The ordering of treatments should be changed across replications
      ABAB Design - Considerations
    • Problems with ABAB designs
      • Absence of reversal
        • The target doesn't return to first baseline levels during the second baseline phase
      • Undesirability of reversing behavior
        • In some instances it is unethical to allow the client to worsen, even for a brief period of time
        • Especially if the behavior has a risk of harming anyone
    • Multiple Baseline Designs
      • Test causality
      • Demonstrating that a target behavior changes when and only when an intervention is applied to that behavior
      • Require highly specified targets and interventions
    • Multiple Baseline Designs Can Be Implemented
      • Across behaviors
        • At least three different target behaviors
      • Across participants
        • With a single intervention being compared across at least three participants who have the same target
      • Across settings
        • with a single intervention being applied to a single participant across at least three different settings
      • Across Change Agents
      • Collect baseline data
        • On at least three targets, participants, or settings/change agents
      • Apply an intervention
        • To only one target, participant or setting
      • After change is demonstrated in the first target, participant or setting
        • Apply an intervention to another single target, participant or setting
      • After change is demonstrated in the second target, participant or setting
        • Apply an intervention to another single target, participant or setting
      Multiple Baseline - Implementing
    • Multiple Baseline Design - Analyzing
    • Problems With Multiple Baseline Designs
      • Interdependent baselines
        • When behaviors change before the intervention is applied to them
      • Inconsistent intervention effects
        • Add ambiguity to conclusions about interventions
      • Prolonged baselines
        • Raise clinical and ethical issues
        • Raise the risk that a behavior may change before an intervention is applied