Introduction to risk ladders and risk scales

The risk ladder/scale shows a range of risks (probability of events) from very low to very high, within the context of an individual risk. The visual format isoften known as a risk scale, but when the benefits or risks are arranged vertically in tabular format, the graphic is called a risk ladder. We made no distinction between them. A risk ladder/scale may carry some technical information such as scientific terminologies and unfamiliar measurement units, and therefore users may require further assistance.

The risk ladder/scale often anchorsthe risk information on other risks for comparison to assist perception of the magnitude of risks, for example anchoring to everyday risks (driving, taking a bath). The rationale for choosing these anchors as comparison is often not justified, and to which extent the risks are relevant to the benefit-risk assessment in question is also unclear (see Ancker 2006).

Risk ladders/scales have been associated with inaccurate and inconsistent interpretation when used to compare benefit-risk balance in medical decision-making, mainly due to the difficulties to correctly interpret values on logarithmic scales (see Dolan 2012).

In terms of reproduction, risk ladders/scales can be produced using any text processing software e.g. Microsoft Word, Microsoft Excel, LaTeX or using other graphical software packages e.g. Tableau, Spotfire, QlikView, IBM Many Eyes and Google Drive. An interactive or dynamic version of the risk ladder/scale could potentially display a change of one risk with time in comparison to other risks or to include tooltips with suitable brief descriptions to support comprehension.