Transcript Chapters 9 & 10 (Richards text) Chapter 8 (Cooper text) – Alternating Treatments Designs in Single-Subject Research Ps534 Dr.

Chapters 9 & 10 (Richards text)
Chapter 8 (Cooper text) –
Alternating Treatments
Designs 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)
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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)
 And…we can clearly determine which
treatment is MORE effective than NO
treatment phase
 So…this 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:
 BUT…we 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)
 Can’t 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 child’s academic task
completion
 How would you do it?
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End
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