Univariate / one-way sensitivity analysis

Univariate/one-way sensitivity analysis allows a reviewer to assess the impact that changes in a certain input (parameter) will have on the output results of an economic evaluation (most frequently those based on a model); this may be referred to as assessing the robustness of the result to that parameter. The parameter of interest should be varied between plausible extremes, preferably justified by review of available evidence or validated by a clinical expert where there is a lack of evidence. This is the simplest form of sensitivity analysis because only one parameter is changed at one time and correlations between parameters are not taken into account. Tornado diagrams are often used to summarise univariate sensitivity analyses testing a set of input variables in turn.