“…A possible solution to these problems might be to avoid the use of field categorization schemes (Bornmann, Marx, et al, 2013), clustering (Waltman & van Eck, 2012), and similarity approaches (Colliander & Ahlgren, 2019), and for each focal paper (that is assessed) to manually search some papers for comparison that are thematically similar (Kostoff, 2002;Waltman, 2016). This solution corresponds to the judgement by Hou, Pan, et al (2019) that field normalization cannot be solved by statistical techniques. The manual collection of papers for the comparison with a focal paper might be possible in the evaluation of small sets of papers; however, it is not practicable for large sets (e.g., all papers published by a university over several years).…”