Inês Teles works for TIS.pt enterprise (www.tis.pt) where she is working on research and consultancy projects covering areas such as cost-benefit analyses and transport model development. By using Palisadeâs (www.palisade.com) @RISK software (www.palisade.com/risk) TiS.pt is able to improve the quality of decision-making by representing traffic demand results in a probabilities distribution histogram, because it allows us to determine the confidence interval for the mean value of traffic demand (or revenue), and identify the most influential input variables for traffic demand through tornado graphics interpretation.