8: single subject design Flashcards
Single subject design
The phenomena of interest are studied using a single object or a small group of research subjects (also referred to as N-of-1 designs or single-subject designs)
Three major types of single-case research
- case studies
- Quasi experimental designs
- experimental designs
Case studies
Refers to a broad array of approaches most often used for observing an individual and reporting on their interactions with variables of interest (e.g. life events, psychological interventions, and so on).
Case studies (advantage)
- Does not require control condition or comparison group + can easily be incorporated into routine clinical work.
- Case studies offer clinicians both a useful research tool as well as a source of data directly relevant to clinical practice
- Provide the opportunity to observe the behavior of interest as it naturally occurs
Case studies (disadvantage)
- Lack methodological requirement to draw valid inferences about the relations among variables.
- They typically do not include design features such as objective assessment, systematic data collection or analysis, specified manipulation of the independent variable
Phineas Gage
The first case study
Single case design
is experimental, hence we must consider internal validity, external validity.
A-B design
Phase a: baseline
Phase b: treatment
if there is a stable baseline, and a clear improvement from the beginning of the phase b: can indicate that treatment has an effect.
Single case experimental designs
It includes a controlled variation of the independent variable and measurement of the effect of this variation allowing the experimenter to examine causal relations between interventions and outcome.
Multiple phases and conditions (single case experimental designs)
Each individual participate in treatment and control conditions. The number and ordering of conditions varies depending on the type of design employed.
The vital element is the inclusion of multiple condition for each subject.
A: indicates non-treatment phase usually referred to as baseline.
B: indicates treatment phase
EXAMPLE: A-B-A = non-treatment baseline phase followed by a treatment phase which is followed by a return to a non-treatment baseline.
Primary research designs
is research you do yourself or get someone else to do it, in contrast to secondary; replication.
Reversal designs, multiple baseline designs
Reversal designs
ABAB: the subjects behavior is first assessed during a baseline (a1), then during an experimental phase in which the manipulation is administered (b1), followed by a return to the baseline phase (a2) during which the behavior is expected to reverse to it baseline leve.
ABAC: in cases where the specified intervention was not effective (did not lead to behavior change), the researcher may wish to test the effect of adding an additional treatment component or a modified version of the intervention.
Multiple baseline designs
Mulitple-baseline designs are those in which the experimental condition is introduced in temporal sequence to different behavior. There is typically only one baseline (that is, no reversal) and one intervention condition.
Internal validity + single subject research
It is always a concern
External validity + single subject research
The lack of it is the major concern with single-subject designs. Generalizability is dressed through multiple replications of the same treatment and designs that produce similar results for a number of different participants.
