Single Case Research Methodology: Chapter 1

Goal of science

To advance knowledge

The process by which we advance knowledge

Research--the systematic investigation and manipulation of variables to identify associates and understand processes that occur in typical contexts

Applied Research

Systematic investigation related to the pursuit of knowledge in practical realms or to solve real world problems. Example: Seeking to identify interventions that result in improved physical activity for children with Down Syndrome.

Single Case Design

Evaluation method used to rigorously test the success of an intervention or treatment on a particular case, and to provide evidence on effectiveness from a small sample size

Independent Variables

Variables manipulated by researchers (interventions)

Dependent Variables

The variables we expect to change given the manipulation (target behaviors)

Baseline Phase

Present pattern before intervention

Intervention Phase

Occurs after a stable baseline is established. DV is measured to determine the effect the IV has on the DV

Internal Validity

Study contains adequate mechanisms for ensuring the outcomes are related to your intervention procedure rather than extraneous factors

Experimental Control

To show that the experimental procedures (intervention) and only the experience procedures are responsible for behavior change

Functional Relationship

The relationship between changes in an independent variable (intervention) and changes in a dependent variable (behavior); a cause-and-effect relationship.

Evidence Based Practice

Intervention procedures that have been scientifically verified as being effective for changing a specific behavior of interest, under given conditions, and for particular participants

What constitutes a "practice?"

A curriculum, behavioral intervention, systems change, or education approach designed to be used by families, educators,, or students with the express expectation that implementation will result in measurable, educational, social, behavioral, or physical benefit.

Reliability

Consistency of measurement; Achieved by defining the target behavior (or event) clearly and concisely so that two independent observers consistently agree on scoring what they observe.

"at the heart of the scientific method"

Replication

Threats to Internal Validity

Variables other than the planned independent variable that could result in changes in the dependent variable.

Nomothetic Research Approaches

Generally based in the natural sciences and are characterized by attempting to explain associations that can be generalized to a group given certain circumstances.

Idiographic Research Approaches

attempt to specify associations that vary based on certain characteristics or contingencies present for the participant or case of interest.

Characteristics of Group Design

Large number of individuals divided into one of two or more study conditions; Includes a control condition and treatment condition

Deductive Analysis

Hypotheses are formulated prior to conducting a study to test a theory

Inductive Analysis

Using a qualitative study approach to collect data and describe themes or trends in the data without offering a theory

Validity

Accuracy of measurement

Quality Indicators for Single Case Research

1. Description of participants and setting

2. Dependent variable

3. Independent variable

4. Baseline

5. Experimental Control/Internal Validity

6. External Validity

Baseline Logic

Participants serve as their own control

Practice-Based Evidence

Using data generated during treatment to inform the process and outcome of treatment.

Similarities Between Practitioners and Applied Researchers

1) Be able to identify and analyze problems

2) Generate creative solutions

3) Implement an intervention in a systematic manner

4) Document the effect of the intervention

5) Act on the date in an ethical and responsible way

History

Refers to events that occur during an experiment, but are not related to the planned procedural changes, that may influence the outcome

Maturation

Refers to the changes in behavior due to the passage of time

Testing

A threat in any study that requires participants to respond to the same test repeatedly , especially during the baseline or probe condition; it is the likelihood that the repeated assessment task will result in a participant behavior change;

Instrumentation

Concerns with the measurement system; They are of particular concern in SCD studies because of repeated measurement by human observers who may make errors

Procedural Infidelity

The lack of adherence to condition protocols by study implementers. If the procedures of an experimental condition (baseline, probe, intervention, maintenance, generalization) are not consistently implemented across behavior episodes, time, interventionists, etc.

Attrition

Refers to the loss of participants during the course of a study, which can limit the generality of the findings, particularly if participants with certain characteristics are likely to drop out.

Selection Bias

Choosing research participants in a way that differentially impacts the inclusion or retention of participants in a study, when compared to the population of interest

Attrition Bias

The likelihood that participant loss (attrition) impacts the outcome of a study

Sampling Bias

Occurs in SCD when researchers use additional, non-explicated, reasons for including or excluding potential participants

Multiple Treatment Interference

When a study participants' behavior is influenced by more than one planned "treatments" or interventions during the course of the study.

Sequential Confounding

The order in which experimental conditions are introduced to participants may influence their behavior

Instability

The amount of variability in data

Cyclical Variability

A specific type of data instability that refers to a repeated and predictable pattern in the data series over time.

Regression to the Mean

Likelihood that following an outlying data point, data are likely to revert back to levels closer to the average value

Adaptation

A period of time at the start of an investigation in which participants' recorded behavior may differ from their natural behavior due to the novel conditions under which data are collected

Hawthorne Effect

Participants' observed behavior not being representative of their natural behavior as a result of their knowledge that they are participants in an experiment

Main Types of Single Subject Designs

1. Reversal Design

2. Multiple Baseline Design

3. Multielement Design

4. Changing Criterion Design

AB Design

One baseline (A) followed by one treatment (B)

Reversal Design

ABA - baseline, treatment, baseline;

ABAB- baseline, treatment, baseline, treatment

Advantages: Simple, yet powerful example of experimental control

Disadvantages: Consider ethics--is it appropriate to discontinue treatment? Irreversibility--behavior may not return to baseline (confounding variable is always the first assumption for irreversibility

Mutliple Baseline Design

Sequential introduction of IV across baselines; Baseline increases across subjects, settings, or behaviors

Which is a reversal design?

Which is a Changing Criterion Design?

Which is a Multielement Design?

Which is a Multiple Baseline Design?