Critical evaluation (CE) of quantity values is part of the core IUPAC mission. CE takes published results and provides the best estimate of the value, with a standard uncertainty, for the use of the chemical community. The time period over which a quantity has been measured could be more than 100 years, and although methodologies change it is not always the case that the newest measurements are the best. Uncertainties with results are all but compulsory now, and retro-fitting uncertainties to old results can be more or less successful. Having determined which studies are to be used, the question of which consensus-building technique is best must be considered. Simply obtaining a mean weighted by the uncertainties with a standard uncertainty of that mean, is likely to underestimate the uncertainty. The more values added into the mean, the smaller the standard deviation of the mean, which is fine if we really are taking from a random population, but not in the reality of the very different measurements available. Methods that take into account ‘dark uncertainty’, including linear pooling, will be described and critiqued.<br/>Having access to data and uncertainty budgets, in theory, provides all a CE needs, but this information must be properly structured and described. Remember ‘measurement uncertainty’ is a property of a measurement result, ‘based on the information used’, and so this can be re-evaluated as new information comes to light. Should an evaluator have to re-calculate all data from scratch? What is the best way of presenting the necessary information?<br/>The “Digital Chemical Information World” will be a hugely important advance for evaluated data, but only if the chemical experts can talk to and understand our colleagues in the Cloud.

Critical evaluation: Uncertainties and consensus values in the cloud

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.