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Chapters 7 & 8 (Richards text)Chapter 9 (Cooper text) –

Multiple-BaselineDesigns 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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Terminology: Multiple-Baseline DesignsFirst, we measure the DV (target behavior) in

baseline (“A” phase) across the following:– Across participants (subjects, clients, learners)– Across settings (examples: school, home, house

of worship)– Across responses (different behaviors but

responses that belong to the same response class)

– Across stimuli (similar to setting but more generic) (SEE NEXT SLIDE)

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Terminology: Multiple-Baseline DesignsSecond, 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.

What confound(s) does this control for? (SEE NEXT)

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Terminology: Multiple-Baseline Designs

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.

What confound(s) does this control for? (SEE NEXT)

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Terminology: Multiple-Baseline Designs

Fourth, when the target criterion is reached for leg 2 THEN we introduce treatment for leg 3 of the design.

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Questions about Multiple-Baseline Designs

•Can I do more than 3 legs? •YES! You may have more than 3 kids to study, or more than 3 responses, or more than 3 settings•In fact, the more legs you use, the higher the internal AND external validity

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Questions about Multiple-Baseline Designs•How do I decide whether to do a multiple-baseline across participants vs. settings vs. responses?•First of all, if you only have one kid to study then this narrows your choice. •If you have a single child and there are 3 or more distinct setting in which you hope the intervention will have an effect, then use “across settings.” See more…

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Questions about Multiple-Baseline Designs•If you do “across settings,” then the target behavior you are studying in each of the 3 settings must be the same (or be very similar). For example, you could study “in seat behavior” at school, church or temple, and at home at the dining table.•In summary, “multiple-baseline across settings” uses 1 kid, 1 behavior, 1 intervention, and 3 or more settings. See more…

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Questions about Multiple-Baseline Designs•When do you use “across responses”?•Again, this would be 1 kid but now you would use only 1 setting•There would now be 3 or more different behaviors. For example, you could study reinforcement of completing homework vs. completing chores vs. completing another household task. The IV is introduced in a staggered fashion.•In summary, “multiple-baseline across responses” uses 1 kid, 1 intervention, 1 setting and 3 behaviors.• See more…

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Questions about Multiple-Baseline Designs•When do you use “across participants (subjects)”?•Usually use this if you had 3 or more kids to study•You would now examine the effects of a single IV on a single behavior in a single setting across the 3 kids. •In actuality, this “single behavior” can be quite complex or consist of many exemplars. For example, the behavior of “object labeling” may be taught with 20 exemplars but we average this to get our DV. See next…

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Questions about Multiple-Baseline Designs•Also, in actuality, the “single setting” can consist of many exemplars. For example, the setting may be “neighborhood stores” but it actually consists of 10 exemplars and we average across the 10 stores.•Notice that this is actually “programming for generalization.” We are NOT interested in whether the behavior is learned better in one store than another or that object labeling occurs better for one object as compared to another. •In a M-B across-participants, we are controlling for confounds like maturation and history.

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Questions about M-B Designs•Okay, so, what if I choose a multiple-baseline across settings and the behavior increases in ALL settings when I introduce the IV in only 1 setting to begin with. Then what?•The functional relationship is CONFOUNDED!

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Questions about M-B Designs•Why did this happen?•Probably, the 3 settings were so similar that the taught behavior GENERALIZED across the other 2 settings when you taught it in one.•From a clinical point of view, this is a good thing•From a researcher’s point of view, it is a prompt to go back to the drawing board because you cannot infer that you have a functional relationship between IV and DV.•Basically this M-B design is now rendered as an AB “design” which is not an experimental design.

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Questions about M-B Designs•AND, what if I choose a multiple-baseline across RESPONSES and all 3 behaviors increase when I introduce the IV for only 1 response to begin with. Then what?•Functional relationship is again CONFOUNDED!

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Questions about M-B Designs•Why did this happen?•Probably, the 3 behaviors were so similar that RESPONSE GENERALIZATION occurred.•From a clinical point of view, this is a good thing•From a researcher’s point of view, it is a big problem. No internal validity! No functional relationship!•Basically this M-B design is now rendered as an AB “design” which is not an experimental design.

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Questions about M-B Designs•Finally, what if I choose a multiple-baseline across SUBJECTS and the behavior changes for all 3 subjects when I introduce the IV for only 1 participant to begin with. Then what?•Functional relationship is again CONFOUNDED!

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Questions about M-B Designs•Why did this happen?•Most likely, you are seeing the effects of either of two confounds: maturation or history.•MATURATION: If the kids were the same age or developmental level, it is possible that each is changing at the same time and the IV was not responsible for the change in DV. For example, consider the transition from 1-word to 2-word utterances in toddlers.•HISTORY: It may be that the school implemented a new lunch program, or the air conditioning was fixed, or a new agency-wide change was made in motivation systems

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Questions about M-B Designs•Why did this happen?•HISTORY: It may be that the school implemented a new lunch program, or the air conditioning was fixed, or a new agency-wide change was made in motivation systems AT THE SAME TIME THAT THE IV WAS INTRODUCED FOR CHILD 1.•So, you are actually seeing a change in the DV due to some other variable, not the IV.•Again, this renders our design as an AB again, an incomplete experimental design.

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