University of Southern Mississippi, United States.
University of Southern Mississippi, United States.
J Sch Psychol. 2017 Aug;63:105-118. doi: 10.1016/j.jsp.2017.03.008. Epub 2017 Apr 13.
Visual analysis is the primary method for detecting the presence of treatment effects in graphically displayed single-case data and it is often referred to as the "gold standard." Although researchers have developed standards for the application of visual analysis (e.g., Horner et al., 2005), over- and underestimation of effect size magnitude is not uncommon among analysts. Several characteristics have been identified as potential contributors to these errors; however, researchers have largely focused on characteristics of the data itself (e.g., autocorrelation), paying less attention to characteristics of the graphic display which are largely in control of the analyst (e.g., ordinate scaling). The current study investigated the impact that differences in ordinate scaling, a graphic display characteristic, had on experts' accuracy in judgments regarding the magnitude of effect present in single-case percentage data. 32 participants were asked to evaluate eight ABAB data sets (2 each presenting null, small, moderate, and large effects) along with three iterations of each (32 graphs in total) in which only the ordinate scale was manipulated. Results suggest that raters are less accurate in their detection of treatment effects as the ordinate scale is constricted. Additionally, raters were more likely to overestimate the size of a treatment effect when the ordinate scale was constricted.
视觉分析是检测图形显示的单个案例数据中治疗效果存在的主要方法，通常被称为“金标准”。尽管研究人员已经制定了视觉分析的应用标准（例如，Horner 等人，2005 年），但分析师对效应大小的高估和低估并不少见。已经确定了几个可能导致这些错误的特征；然而，研究人员主要关注数据本身的特征（例如，自相关），而较少关注图形显示的特征，这些特征在很大程度上由分析师控制（例如，纵坐标缩放）。本研究调查了纵坐标缩放（图形显示特征之一）的差异对专家判断单个案例百分比数据中存在的效应大小的准确性的影响。32 名参与者被要求评估八个 ABAB 数据集（每个数据集呈现零、小、中、大效应各两个），以及每个数据集的三个迭代（总共 32 个图形），其中只有纵坐标尺度被操纵。结果表明，随着纵坐标尺度的缩小，评分者在检测治疗效果时的准确性降低。此外，当纵坐标尺度缩小时，评分者更有可能高估治疗效果的大小。
