Nature vs science: citation impact by field

Field	Nature:%3Cbr /%3ERank	Nature:%3Cbr /%3EImpact	Science:%3Cbr /%3ERank	Science:%3Cbr /%3EImpact	Field impact %3Cbr /%3E(cites/paper)
Agricultural sciences	1	156	2	78	6
Biology/biochemistry	4	137	3	150	16
Chemistry	1	175	2	156	10
Clinical medicine	1	257	2	251	12
Environment/ecology	2	110	3	99	10
Geosciences	2	58	1	64	9
Immunology	3	190	2	193	20
Materials science	2	126	1	155	6
Microbiology	1	140	2	119	15
Molecular biology/genetics	2	135	1	136	24
Neurosciences	3	134	2	141	18
Pharmacology/toxicology	3	105	1	170	11
Physics	1	137	2	131	8
Plant and animal sciences	3	91	2	100	7
Psychiatry/psychology	5	59	1	84	10
Space science	2	50	3	46	13

The golden rule of citation analysis: compare like with like. So how can one compare influential journals such as Nature and Science, which publish research articles across a range of disciplines, with discipline-specific titles? Since different fields exhibit different average rates of citation, placing a field-specific journal against a multi­disciplinary one would amount to an “apples and oranges” comparison.

To allow top journals in a field to be ranked against Nature and Science, and vice versa, Thomson Reuters analyses each paper in these two multi­disciplinary journals and assigns it to a specific field defined in the database. This is accom­plished using an algorithm that summarises the journals cited by each article and the journals that cite each article. In effect, Thomson Reuters creates field-specific versions of Nature and Science.

The table above provides the citations per paper (impact) ranking for Nature and Science in each field in which they published significantly from 1999 to 2009. Citations counted were to the same papers over the same period. Thus, the average citation rates (rounded to the nearest whole number) represent a blended rate in terms of the age of the articles cited.

As is evident, Nature and Science often top field-specific titles in each discipline in terms of citation impact, frequently capturing first and second place. Very often, the difference in impact between the two titles is small, such as in molecular biology and genetics. In other fields, the differences in impact, if not in rank, are striking: for example, agricultural sciences (advantage Nature) and pharmacology and toxicology (advantage Science).

The far-right column provides the (age-blended) citation impact for each field for the period covered. These figures can be compared against those for Nature and Science to reveal just how much more impact, on average, papers published in these two powerhouse journals have than the group average for all papers in the field.

For more information, see: http://scientific.thomsonreuters.com/products/esi