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Multiple Baseline Designs. Multiple Baseline Design. A series of A-B designs that Have baselines of different lengths The different graphs are called tiers, legs, or panels. MBD Methods. At least 2 baselines are conducted simultaneously

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multiple baseline design
Multiple Baseline Design
  • A series of A-B designs that
    • Have baselines of different lengths
  • The different graphs are called tiers, legs, or panels
mbd methods
MBD Methods
  • At least 2 baselines are conducted simultaneously
  • First, we measure the DV (target behavior) in baseline across
    • Behaviors
    • Settings
    • Participants
  • Second, we wait for all 3 baselines to be stable and then introduce treatment for only one leg of the design. The other legs remain in baseline.
  • Third, when the target criterion is reached for leg 1 (the one in treatment) THEN we introduce treatment for leg 2 of the design. The third leg remain in baseline.
  • Fourth, when the target criterion is reached for leg 2 THEN we introduce treatment for leg 3 of the design.
slide4

Demos experimental control when behavior changes only when intervention is implemented for each baseline

Treatment effect

Treatment effect

slide5

Demos experimental control when behavior changes only when intervention is implemented for each baseline

Treatment effect

Trend, level, and variability don’t change

slide6

Treatment effect

No treatment effect

Treatment effect

  • Demos experimental control when behavior changes only when intervention is implemented for each baseline
slide7

Prediction

Tx Effect

Prediction

Verific

Replication

Prediction

Verification

Replication

slide8

Beh. #1

Beh. #2

EXPERIMENTAL CONTROL ?

slide9

Beh. #1

Beh. #2

EXPERIMENTAL CONTROL ?

slide10

Beh. #1

Beh. #2

EXPERIMENTAL CONTROL ?

advantages and limitations
ADVANTAGES AND LIMITATIONS
  • Advantages
    • Useful when behaviors are not reversible
    • Useful when intervention cannot or should not be removed
    • Allows you to assess generalization
  • Disadvantages
    • Some participants might receive lengthy baselines
    • Requires multiple participants, situations, or behaviors
    • Weaker experimental control than reversal because verification is shown with other participant, situation, or behavior
    • If baseline data change when implementing tx on another tier
      • Great clinically!
      • Disaster experimentally…you can’t demonstrate experimental control b/c you can’t tell if some extraneous variable affected them both
        • You’re left with an A-B design
        • May result from generalization
      • Similar problem if data only change when implementing the IV for 1 of the tiers – did something other than the IV cause the change in that 1 (your tx doesn’t really work at all)
guidelines for using mbd
Guidelines for using MBD
  • 2-tier MBD is a complete experiment
    • 3 will demonstrate more experimental control and make it more likely to published
    • The more tiers, the more internal validity and external validity
    • Green says at least 3
  • Make sure the settings, participants, behaviors are independent
  • Combine MBD with reversal or alternating txs design if possible
  • Vary the baseline lengths significantly
    • Allows you to show stable responding in baseline data when implementing tx on another tier
    • Controls for practice effects/reactivity to observation and measurement
  • When using MBD clinically, may not be able to wait for stability on all baselines – get “reasonable stability” on all and begin tx with the most stable BL first
mbd across behaviors
MBD Across Behaviors
  • 2 or more different behaviors of the same participant
mbd across settings
MBD Across Settings
  • Same behavior of same participant in 2 or more different settings, situations, stimuli
  • Could be across therapists
mbd across participants
MBD Across participants
  • Same behavior of 2 or more different participants (or groups)
  • Should be matched on an important feature
  • Would you use 2 roommates?
    • 2 learners in same classroom?
multiple probe design
Multiple probe design
  • Instead of collecting data during every session, probes are conducted
  • Useful if
    • You don’t have resources for frequent testing
    • You don’t want to expose the participant to baseline conditions frequently
    • Strong a priori assumption of stability (the target behavior isn’t likely to be emitted)
    • You suspect reactivity to assessment or change in behavior due to testing
  • May just use probes in BL and then collect data every session in tx phase
    • But if reactivity is the issue, continue using probes in tx
  • Ideally, you should still have at least 3 data pts in a phase and demonstrate stability
    • If probes are variable, may need to use continuous
    • Stronger exp control if conduct short continuous BL just before tx
  • Make sure to conduct probes before and after changes in other tiers
nonconcurrent mbd
Nonconcurrent MBD
  • AKA Natural MBD
  • Tiers are evaluated consecutively, not concurrently
  • A-B designs with varying baseline lengths vertically aligned and visually inspected as a concurrent MBD
  • Not as strong for concurrent MBD for demonstrating exp control
    • Controls for maturation threat, but not history (no verification)
    • But may be great for clinicians!
  • Must specify which type you’re using!
carr 2005
Carr (2005)
  • Concurrent MBDs often align session data pts from different participants above the same x-axis numbers
  • Problem with this?