CSDS 200: Exam #2 - Module 5

Where does control come from in single-subject research

Dependent variables are measured continuously, graphed, and analyzed using visual inspection (only way to establish control is by observing): predicition, verification, and replication

Prediction

once they level out they will likely continue

Verification

verify a change occurred when the independent variable was manipulated

Replication

replicate so we can confirm that the cause of the change was the independent variable and not another variable

How are treatment phases used within single-subject research designs

At minimum, these conditions include baseline (A) and intervention (B) phases

Baselines establish a benchmark against which the participant’s behavior in subsequent conditions can be compared

Baseline data must:

Be stable

lack a clear trend of improvement

include at least 3 points to establish stability of the dependent variable

Benefits of single-subject designs

Often, less costly to implement

Can be used to establish the viability of a treatment method prior to expending the resources needed to conduct a study utilizing a group design

Help determine effective treatments for specific clients

Limitations of single subject designs

Individual studies cannot demonstrate external validity

Advantages of AB design

serves as a building block for true experimental designs

Disadvantages of AB design

Cannot establish efficacy; however, they can demonstrate improvement

Does not sufficiently control for many threats to internal validity and, therefore, does not demonstrate experimental control

Demonstrates a potential link between the independent and dependent variables, but not necessarily causation

Advantages of ABA and ABAB designs

Provide degree of experimental control while being easy/straightforward to plan and implement

Often require fewer participants, resources, etc.

In ABAB provides more replication, demonstrating even greater control

Disadvantages of ABA and ABAB designs

If the DV does not reverse in the second “A” phase, a functional relationship cannot be claimed

As a result, may be difficult to implement for some DVs

Ethical issue associated with withdrawing an apparently effective intervention

Advantages of Multiple Baseline and Multiple Probe Designs

Avoid the disadvantage of a withdrawal of the IV (always end in a treatment phase)

Appropriate for behaviors that may not return to baseline levels

Disadvantages of Multiple Baseline and Multiple Probe Designs

Treatment is withheld for a time for certain participants, behaviors, and/or settings

Potential for generalization which would serve as a threat to validity

It may not be appropriate to use a multiple-probe design if there is significant variability in the DV

Advantages of Multiple Treatment Designs

Useful when determining the effects of multiple treatment methods

Provide strong internal validity

Helpful to consult when selecting a treatment method to use with a given client

Disadvantages of Multiple Treatment Designs

Can only compare adjacent phases

Potential multiple-treatment interference

If the DV does not reverse in the second “A” phase, a functional relationship cannot be claimed

Advantages of Alternative Treatment Designs

Useful in comparing the effects of two or more IVs

Allow multiple comparisons in relatively few sessions (very efficient way to compare independent variables)

Disadvantages of Alternative Treatment Designs

Potential multiple-treatment interference

Pre-experimental AB Design graph

ABAB Design Graph

ABA Design Graph

Multiple Baseline Designs Graph

Multiple Probe Design Graph

Changing Criterion Design Graph

Multiple Treatment Design Graph

Alternating Treatment Design Graph

Which single-subject treatment designs can be used to examine. theefficacy of more than one independent variable

Alternating treatment designs and multiple treatment designs