The interests of chemical engineering researchers overlap with the interests of researchers from other sciences such as chemistry, biology, applied physics, and applied mathematics, as well as those from other engineering disciplines such as electrical, biological/biomedical/bioengineering, mechanical, civil, or materials sciences. As a result, the Panel opted to refine the search of publications and explore the relative contributions by chemical engineers in the United States and other regions of the world among themselves and vis à vis researchers from other disciplines.
Affiliation of a researcher with a group that carries the name “chemical engineering” limits the analysis of relative research competitiveness across the world. For example, researchers in certain countries of the European Union and Japan, who are by U.S. definition chemical engineers, are not affiliated with units carrying the name “chemical engineering” in their home institutions. Refinement of the search through the mechanisms available in Web of Science® is difficult, impractical, or impossible. Therefore, the Panel recognizes that a certain ambiguity as to what constitutes a proper comparison of chemical engineering publications by various regions of the world is present throughout Chapters 3 and 4 of this report. To overcome this ambiguity, the Panel has added an analysis of relative competitiveness by U.S. and non-U.S. researchers in each subarea across disciplinary distinctions.
Publication rates and citations per paper vary widely among the various subareas of chemical engineering, and the Panel resisted making broad comparisons of different subareas in terms of these metrics. The only exception is the analysis of publications in the journals with broad coverage of chemical engineering, namely, AIChE Journal, I&EC Research, and Chemical Engineering Science, because the Panel wanted to assess the trends of publication rates in various subareas of chemical engineering over time.
The number of papers in the top 100 (or 50, or 30, depending on subarea) most-cited papers in a particular subarea was used as a metric to assess impact. The Panel recognizes the potential pitfalls of such a metric, but it resolved that it is quite representative of relative significance of research contributions, especially if comparisons are limited within the scope of a specific subarea of chemical engineering.