An Empirical Model of Slope Ratio Comparisons

Comparing slopes is a fundamental graph reading task and the aspect ratio chosen for a plot influences how easy these
comparisons are to make. According to Banking to 45°, a classic design guideline first proposed and studied by Cleveland et al.,
aspect ratios that center slopes around 45° minimize errors in visual judgments of slope ratios. This paper revisits this earlier
work. Through exploratory pilot studies that expand Cleveland et al.’s experimental design, we develop an empirical model of slope
ratio estimation that fits more extreme slope ratio judgments and two common slope ratio estimation strategies