In an experimental design, a single subject design b or a single case study design is the most frequently used research design in the field of applied psychology, education, and human behavior in which the subject functions as its own control , rather than using another individual/group. Researchers use a single subject design because the design is sensitive to individual organism differences vs group designs that are sensitive to group averages. Often there will be a large number of subjects in research studies using a single subject design, however - since the subject serves as their own control, this is still a single subject design. This design is used primarily to evaluate the effect of various interventions in applied research.
Video Single-subject design
Requirements
The following are the single subject design requirements:
- Continuous assessment: Individual behavior is observed repeatedly during the intervention. This ensures that any treatment effects are observed long enough to convince scientists that treatments produce lasting effects.
- Initial assessment: Before treatment is applied, the researcher should look for behavioral trends. If the treatment reverses the initial trend (eg, the situation gets worse over time in the baseline but the treatment reverses this trend) then this is strong evidence showing (though not proving) the effects of treatment.
- Variability in data: Because behavior is repeatedly assessed, a single subject design allows the researcher to see how consistently treatments change behavior over time. Large group statistical designs usually do not provide this information because repeated assessments are usually not taken and individual behavior in groups is not researched; instead, the means of the group were reported.
Maps Single-subject design
Phase in the design of a subject
- Baseline : this phase is the phase in which researchers collect data on the dependent variable without any intervention in place.
- Interventions : this phase is the phase in which the researcher introduces an independent variable (intervention) and then collects data on the dependent variable.
- Reversal : this phase is the phase in which the researcher deletes the independent variable (reversal) and then collects the data on the dependent variable.
It is important that the data is stable (stable trend and low variability) before the researcher moves to the next phase. The design of a single subject produces or approaches three levels of knowledge: (1) descriptive, (2) correlational, and (3) causal.
Design flexibility
Single subject designs are preferred because they are very flexible and highlight individual differences in response to intervention effects. In general, a single subject design has been shown to reduce the interpretation bias for counselors when performing therapy.
Interpretation of data
To determine the effect of independent variables on the dependent variable, the researcher will graph the data collected and visually check the differences between phases. If there is a clear distinction between the baseline and the intervention, and then the data returns to the same trend/level during the reversal, the functional relationship between variables is inferred. Sometimes, visual checks of data show results that the statistical tests fail to find.
Researchers using a single subject design begin with graphical analysis . During the baseline, data are collected repeatedly and then drawn on interesting behavior. It provides a visual representation of the subject's behavior prior to the implementation of the intervention. It is important that some (three to five are often recommended) data points collected during the initial to allow the researcher to describe the effect on the target behavior during the intervention.
In interpreting, the general strategy of all single subject research is to use the subject as their own control. The experimental logic holds that the subject's baseline behavior will match its behavior in the intervention phase unless the intervention does something to change it. This logic then applies to the exclusion of confusion, which needs to be replicated. It is a replication within the subject and allows for the determination of functional relationships. Thus the objectives are:
- Demonstration
- Verify
- Replication
Limitations
The research design is traditionally planned in such a way that most of the details about to whom and when the intervention will be introduced are decided before the start of the study. However, in a single subject design, this decision is often made when data is collected. In addition, there is no agreed-upon rule for the phase of change, so - this may lead to conflicting ideas about how research experiments should be conducted in a single subject design.
The main criticisms of one subject design are:
- The carry-over effect : Results from the previous phase are taken to the next phase.
- Order effects : The order (sequence) of intervention or treatment influences what results.
- Irreversibility : In some withdrawal designs, once a change in an independent variable occurs, the dependent variable is affected. This can not be undone only by deleting independent variables.
- Ethical issues : Withdrawal of care in the design of withdrawals can sometimes lead to ethical and feasibility issues.
History
Historically, single subject designs have been closely linked to behavioral experimental analysis and applied behavioral analysis.
See also
- N of 1 trial
- Single subject research
References
Further reading
- Kazdin, Alan (1982). One Case Research Design . New York: Oxford University Press. ISBN: 0-19-503021-4.
Source of the article : Wikipedia
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