Special Education, Texas Tech University, Lubbock, TX, USA.
Special Education, University of Alabama, Tuscaloosa, AL, USA.
J Intellect Disabil Res. 2022 Oct;66(10):743-755. doi: 10.1111/jir.12966. Epub 2022 Aug 12.
Estimates of treatment effect size from single case experimental design (SCED) data may be impacted by the direction for treatment effects (i.e. ascending or descending slope for the dependent variable). Estimating effect sizes for treatments designed to decrease behaviour are potentially more restricted because the intended direction for treatment is zero (i.e. an absolute basal). Conversely, effect sizes for interventions that increase behaviour are less restricted due to a relatively unconstrained ceiling from a pure measurement standpoint (i.e. no absolute ceiling). That is, treatments that increase behaviour have a broader range of possible effect size values as the ceiling is only limited by demand characteristics and the learners' skills and motivation to exhibit the behaviour.
The current study represents a preliminary analysis of the mean and range of SCED effect sizes for treatments designed to either increase or decrease target behaviour. A within-case Cohen's d measure that was developed for SCED data was used to estimate treatment effect sizes.
Results indicated that the mean and range of effect size values for treatments that increased behaviour were significantly greater compared with treatments that decreased behaviour.
Results are discussed in terms of developing standards, or best practices, specific to interpreting effect size values and meeting quality control requirements for inclusion of the data set in future SCED meta-analytic studies estimating treatment effect size. Specifically, preliminary results suggest that benchmarks for low, medium and high SCED effect size values need to be developed separately for treatments that increase or decrease levels of the dependent variable.
来自单病例实验设计（SCED）数据的治疗效果大小估计可能会受到治疗效果方向的影响（即因变量的上升或下降斜率）。为降低行为而设计的治疗的效果大小估计可能受到限制，因为治疗的预期方向为零（即绝对基线）。相反，由于从纯粹测量的角度来看，干预措施增加行为的效果大小限制较少（即没有绝对上限），因此效果大小限制较小。也就是说，增加行为的治疗方法具有更广泛的可能效果大小值范围，因为上限仅受到需求特征以及学习者表现行为的技能和动机的限制。
本研究初步分析了旨在增加或减少目标行为的治疗方法的 SCED 效果大小的平均值和范围。为 SCED 数据开发的基于单个案例的 Cohen's d 度量用于估计治疗效果大小。
结果表明，与降低行为的治疗方法相比，增加行为的治疗方法的效果大小平均值和范围明显更大。
根据制定标准或最佳实践的角度，讨论了结果，这些标准或最佳实践专门用于解释效果大小值，并满足将数据集纳入未来估计治疗效果大小的 SCED 元分析研究的质量控制要求。具体来说，初步结果表明，对于增加或减少因变量水平的治疗方法，需要分别为低、中和高 SCED 效果大小值制定基准。
