SUPPLEMENTARY COMMENTS 



Dr. Saunders Mac Lane has contribuleci the following technical comments on the validity of 

 the sampling procedures underlying some of the material in Chapter One. While some of the 

 questions have been dealt with in the text itself, the National Science Board believes they should be 

 presented in their entirety here and expresses its appreciation to Dr. Mac Lane for his observations. 



There are real uncertainties and difficulties in 

 interpreting one of the figures and one of the 

 tables in Chapter 1. 



Figure 1-7, on page 14, gives the percent 

 distribution of scientific literature by selected 

 field for each of six countries. As the accom- 

 panying text indicates, it is hoped that these 

 results will indicate approximately the way in 

 which these countries differ in their emphasis on 

 various fields of scientific research. However, 

 this interpretation depends on whether the data 

 are representative. The data came from a count 

 of articles, notes, and reviews in a sample of 

 2,121 scientific journals. This sample is essen- 

 tially the list of journals currently used by the 

 Science Citation Index and chosen from ap- 

 proximately 26,000 science and technology 

 journals currently published in the world. 

 Clearly the distribution of this data depends on 

 the choice of the sample. If in a given country the 

 sample over-represents journals in one science, 

 say chemistry, then the percentage over- 

 represents the emphasis of that country on 

 chemistry. At present unfortunately no real 

 evidence is available as to whether the sample is 

 representative. There is even evidence that the 

 sample is not representative as of certain fields. 

 One such is mathematics (not represented in 

 Figure 1-7). The 2,121 journals include 122 

 journals in mathematics. Among them at least 31 

 are published in the United States and only seven 

 in Russia. This is an unbalanced representation 

 because this same report in table 1-6 indicates 

 correctly that the U.S. and the U.S.S.R. each 

 publish about 30 percent of the total world 

 literature in mathematics. Hence any percent 

 emphasis of U.S.S.R. on mathematics calculated 

 from these data would be wrong. This same 

 difficulty may well occur in other fields. 



Page 13 gives a small table of the CITATION 

 INDICES of selected scientific literature by 

 selected fields. This citation index is a ratio 

 calculated from the same 2,121 journals; the 

 percentage of all citations in the field which are 

 citations of the publications of the country in 

 question, is divided by the percentage of articles 

 in the field published by that country. These 

 citation indices produce a rank order of the six 



countries in each of the six fields of science. In 

 five of these six fields, the U.S. ranks first and 

 the U.S.S.R. ranks last, while in four of these six 

 fields France ranks next to last. 



Before interpreting these rankings one should 

 recognize the limitations of this calculation. In 

 the first place, it depends on the representative 

 character of the sample of journals used; the 

 indications above are that this sample may not be 

 representative. Secondly, it depends on citations 

 and citations in turn depend on the availability of 

 the literature to cite. It is evidently much easier 

 to cite a paper written in your own language and 

 present in your own university or city library. 

 This fact, plus the general use of the English 

 language, may have a lot to do with the ranking 

 of Russia, since many Russian journals are not 

 extensively distributed, many Western scientists 

 can't read Russian, and many Russians may not 

 see Western journals. 



I have not been able to quantify these effects. 

 However, table l-7b in the appendix does 

 indicate a self-citation index (e.g., Russian 

 papers cited in other Russian papers). In each of 

 six fields of science Russia has by far the highest 

 self-citation index, while in chemistry it is 

 outranked only by West Germany and in 

 engineering only by France. These indices do 

 suggest one possible effect upon citation rates. 



Citation rates also depend on the scientific 

 habits of the country in question. For example, 

 French science in several fields is remarkable 

 because there are relatively few scientists, 

 including many of exceptional quality and 

 insight; such a small-scale, high quality effort 

 would be swamped in a citation index. Moreover, 

 much of French scientific publication appears in 

 the Comptes Rendus of the French Academy of 

 Sciences. Notes published there are limited to 

 four pages. This results in many scientific 

 papers, each with little room for citations. Such a 

 publication habit, to say nothing of the cen- 

 tralization of French science in Paris, means that 

 the citation indices may not properly represent 

 the balance or quality of French science. 



Saunders Mac Lane, Member 

 National Science Board 



242 



■i^ U.S. GOVERNMENT PRINTING OFFICE . 1976 0-599-66) 



