Problems with Scoring Methods and Ordinal Scales in Risk Assessment Risk Assessment Methods Based on Scoring Methods That Rate The

4 Risk assessment methods based on scoring methods that rate the 5 severity of each risk factor on an ordinal scale are widely used and 6 frequently perceived by users to have value. We argue that this 7 perceived benefit is probably illusory in most cases. We begin by 8 describing a number of common scoring methods currently used to 9 assess risk in a variety of different domains. We then review the 10 literature on the use of ordinal scales in risk analysis, the use of 11 Bverbal scales[ for eliciting estimates of risks and probabilities, and 12 the extensive research about peculiar human errors when assessing 13 risks. We also supplement this overview with some data of our own. 14 When these diverse kinds of evidence are combined, the case against 15 scoring methods is difficult to deny. In addition to the evidence 16 against the value of scoring methods, there is also a lack of good 17 evidence in their favor. We conclude our overview by reviewing the 18 reasons why risk assessment approaches should describe risk in 19 terms of mathematical probabilities.