Single-case design is a research methodology that entails repeated measurement to assess the influence of an independent variable on a dependent variable over time. Data collected in this manner are regularly analyzed using visual analysis of data displayed in a linear graph. Although there is agreement regarding critical elements of visual analysis, research has highlighted poor reliability between raters. One potential contributor to this poor reliability are variations in visual presentation of the data during construction of the linear graph. The current study sought to determine the potential effect of one common variation, scaling of the x-axis by intervention session or by calendar date. Results of the study indicated a significant effect of x-axis scaling, with data presented by session, rather than by calendar day, judged as reflecting larger intervention effects, Z = 1981, p < 0.001. This effect was consistent across graphs displaying treatment effects of various magnitudes. Results of the study are discussed with the respect to the standardization of visual representation of single case data.