SOCW 6121 Week 9 Single-System Design Evaluation Example

Days Out of the House, Week by Week: A Single-System A-B Evaluation of a Client's Progress Toward Morning Structure, With a Phase-Lined Graph Read for Level, Trend and Variability and an Acceptance Letter Named as the Strongest Rival Explanation

Student Name

Walden University

SOCW 6121: Advanced Clinical Practice II

Instructor Name

Month Day, Year

Days Out of the House, Week by Week: A Single-System A-B Evaluation of a Client's Progress Toward Morning Structure, With a Phase-Lined Graph Read for Level, Trend and Variability and an Acceptance Letter Named as the Strongest Rival Explanation

Target and Measures

This evaluation asks whether Dale, the composite client of this course's case, made progress on the first objective set in Week 2: getting out of the house, for a reason he had planned, on four days a week. The primary measure is the number of days each week on which he left the house for a purpose he had planned the evening before, recorded by Dale on a card by the door and reviewed at each session. A planned purpose included a job-related errand, a class, a visit or an appointment; unplanned trips did not count. A second measure ran alongside: an evening rating of how stuck he felt that day, on a self-anchored scale from 0, "moving and doing things," to 10, "completely stuck," with the anchors written in his words.

Design

The design is an A-B design, the basic single-system design that Bloom et al. (2009) describe for evaluating one's own practice. Phase A, the baseline, ran for three weeks before the structured plan began; Dale kept the card during those weeks at the worker's request, after the second session. Phase B, the intervention, ran for eight weeks and included the behavioral activation steps from the CBT work, the motivational sessions about the certificate and the solution-focused session. Kazdin (2011) notes that an A-B design can show whether change coincided with an intervention but cannot by itself rule out other explanations, because it has no return to baseline and no second case.

The Graph

Figure 1

Days per Week Leaving the House for a Planned Purpose, Baseline and Intervention

Data are invented for this composite example. The dashed vertical line separates baseline (weeks 1 to 3) from intervention (weeks 4 to 11). The dashed horizontal line marks the baseline median. The acceptance letter from the certificate program arrived during week 8.

Reading the Graph

Level. The baseline level was low: one, zero and one days a week, a median of one. During the intervention, the level rose to a median of 3.5 days, and in the last four weeks Dale left the house for a planned purpose on four or five days each week, meeting the objective.

Trend. The baseline was flat. The intervention phase shows a steady upward trend over the first five weeks, from two days to four, followed by a plateau between four and five. The rise began in the first week of the intervention, which fits the timing of the plan, though the steepest single increase, from three days to four, came in week 8.

Variability. Variability was low in both phases. Week-to-week changes were never larger than one day, which makes the overall shift easier to read than it would be with scattered data.

The second measure moved in the opposite direction, as expected. Dale's average evening rating of feeling stuck fell from 7.4 during baseline to 4.1 in the last four intervention weeks.

Threats to the Conclusion

History is the strongest rival explanation. During week 8, Dale received a letter accepting him into the logistics certificate program, which would begin the following month. Some of the change in weeks 8 to 11 may reflect that news rather than the intervention: an acceptance gives a person a reason to plan trips, such as visiting the campus or buying supplies. The upward trend before week 8 makes it unlikely that the letter explains all of the change, but it may explain some of the later level. Kratochwill et al. (2013), setting out standards for single-case designs, require repeated demonstrations of an effect across phases or cases before a design can support a strong causal claim, and an A-B design does not meet that standard.

Other threats are smaller but present. Self-monitoring itself can change behavior, since recording trips may encourage more of them. Maturation is possible, as some recovery after a layoff can occur with time alone. And the measure depends on Dale's own recording, though the worker reviewed the cards each week and they matched his accounts in session.

Conclusion

The data show that Dale's days out of the house rose from a baseline median of one to four or five in the last four weeks, meeting his objective, and that the change began when the intervention began. The design cannot show that the intervention caused the change, and the acceptance letter is a plausible contributor to the later weeks. For practice purposes, the evaluation supports continuing the plan and suggests that tying structure to the certificate, once it begins, may help maintain the gain. A follow-up measurement at one and three months after termination, using the same card, would show whether the gain holds once regular sessions end.

References

Bloom, M., Fischer, J., & Orme, J. G. (2009). Evaluating practice: Guidelines for the accountable professional (6th ed.). Pearson.

Kazdin, A. E. (2011). Single-case research designs: Methods for clinical and applied settings (2nd ed.). Oxford University Press.

Kratochwill, T. R., Hitchcock, J. H., Horner, R. H., Levin, J. R., Odom, S. L., Rindskopf, D. M., & Shadish, W. R. (2013). Single-case intervention research design standards. Remedial and Special Education, 34(1), 26-38. https://doi.org/10.1177/0741932512452794