Chapters 9

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Chapters 9 10 (Richards text)Chapter 8 (Cooper
text) Alternating TreatmentsDesigns in
Single-Subject Research

• Ps534
• Dr. Ken Reeve
• Caldwell College
• Graduate Programs in ABA

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Review Single-Case Experimental Designs Issues

• For each design we will ask the following
• Does the design allow us to see a change in DV
  (without regard to whether it was caused by the
  IV)?
• Does the design allow us to infer a functional
  relationship between IV and DV? Why does it
  allows this?
• What threats to internal validity (confounds)
  does the design control for?
• What ethical issues are important to know about
  using a particular design?

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Purpose Alternating Treatments Designs

• Main Purpose We examine the effects of TWO (or
  more) DIFFERENT IVs (treatments) on a SINGLE DV
  (target behavior)
• Can be done with a baseline
• Can be done without a baseline
• Can also end on a single treatment
• Also called MULTI-ELEMENT DESIN
• Also called MULTIPLE-SCHEDULE DESIGN

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How To Do Alt Treatment Designs

• Begin with single participant (each participant
  is a SEPARATE experiment and serves as his or her
  own control like in a withdrawal design)
• Take baseline IF POSSIBLE (not necessary to
  demonstrate experimental control but desirable)
• When you implement TREATMENTS, you rapidly
  alternate between them from one session to the
  next
• Useful to have cue or discriminative stimulus
  to signal to child what condition is in effect
• You can either COUNTERBALANCE or randomly present
  the conditions (this is done so that we reduce
  possible confound of order/sequence effects)

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Types of AT Designs No Baseline Type
Notice that no treatment phase (A) takes place
of a regular BL
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Issues About No Baseline Type of AT Designs

• Issues We can clearly determine which treatment
  is MORE effective than other treatment(s)
• Andwe can clearly determine which treatment is
  MORE effective than NO treatment phase
• Sothis means we DO have a functional
  relationship and we DO have good internal
  validity
• BUT

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Issues About No Baseline Type of AT Designs

• BUTwe do not know whether the picture we get of
  the no treatment phase is what it would look
  like if we had a regular baseline
• A small point, perhaps, but design is slightly
  stronger if you have a baseline
• Ethical issues may preclude a regular baseline,
  though!

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Types of AT Designs With Baseline Type
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Types of AT Designs End on Single Treatment Type
You end with the better treatment!
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General Advantages AT Designs

• Avoids withdrawal of treatment found in an ABAB
  reversal design
• Avoids ethical problems of long no treatment
  baselines (if you do the AT with no baseline
  design)
• Allows us to determine more (most) effective
  treatment very economically

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General Disadvantages AT Designs

• May be unable to do AT design if treatments have
  carry-over effects (so need to determine if this
  is a problem)
• Cant do this if learning (change in behavior) is
  permanent since this would result in no
  reversibility of data
• May be difficult to do AT if student/client is
  not skilled in discrimination among conditions!

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Design a study using AT Design

• Question You wish to compare the effects of two
  different reinforcement procedures on a childs
  academic task completion
• How would you do it?

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End