Analysis of the proxy approach. After identifying datasets con-110 taining proxy data, the exact implementation was analyzed by comparing with the industry raw data of the chemical plant site behind the proxy data. Also, additional analyses were conducted to check the consistency of using proxy data, the documentation of relevant process flows, and the appro-115 priateness of using proxy data (e.g. whether process-specific data had been available at the time of dataset creation). Furthermore, a mapping of the use of proxy data in the bulk data from the different databases to evaluate the impacts of using proxy data. Before conducting this comparison, we first eliminated data inconsistencies. Hence, the gate-to-gate analysis of the ecoinvent, IDEA and IHS Markit datasets was performed by merging each of the electricity and heat inputs, and converting them to primary energy demands under the assumptions of 40 % and 80 % net efficiency, respectively. This was done to harmonize the datasets and enable separating out the influence of proxy data on the final results. A small number of the IDEA datasets that used the system expansion principle were excluded from the analysis, as this principle is not employed in the ecoinvent database. Co-product allocation based on prices was additionally carried out for the IHS Markit datasets to transform multi-output processes into single-output processes. The price data for that was directly obtained from the IHS Markit datasets. Thus, economically allocated singleoutput datasets from IHS Markit were derived in line with the main allocation approach of the ecoinvent database for chemicals. Then, the estimated primary energy demands of processes in the ecoinvent datasets were compared to the corresponding gate-to-gate primary energy demands in the IDEA and IHS Markit datasets.