Bibliometric-based Study of Scientist Academic Genealogy

The academic genealogy fecundity is the basic guarantee that an academic genealogy will develop. The intrinsic motivation of academic genealogy reproduction has been variously reported as personal character, scientific spirit, and discipline development (Kelley & Sussman, 2007; Li & Xia, 2013; Wuyunqiqige, 2009). Besides constructing a genealogy chart of intuitive expression, Russell and Sugimoto (2009) and David and Hayden (2012) developed quantitative indices for characterizing academic genealogy. Russell and Sugimoto suggested eight indicators (A, C, A+C, T, G, W, T_A, T_D) of genealogy reproduction ability. They considered the reproduction conditions of the academic genealogy, mainly, the cultivation of students by tutors and the inheritance promotion and development of the genealogy. As members of the dissertation committee have less influence on students, their roles are ignored in the present study. Consequently, we exclude the C and A+C indices, and adopt the remaining six indicators (A, T, G, W, T_A, T_D) as the evaluation dimensions in the reproduction ability analysis of the academic genealogy.

The academic influence forces of a scientist refers to the degree to which a scientist is recognized by academia or peers. It mainly reflects the academic status of a scholar in the field and the degree to which academic peers and the general public recognize, value and cite their scientific research results. As is well known, an academic genealogy is influenced by the joint efforts of every member in the genealogy, but the academic influences and the academic contributions differ among the members. In this subsection, we quantitatively describe the total influence forces of a genealogy and identify its most influential members in each generation. For the academic influence of academic genealogy, we had a detailed discussion in our previous study (Lv & Chang, 2017).

Based on the academic genealogy fecundity and academic influence index derived in previous studies, we constructed a two-dimensional evaluation system for academic genealogies. The indices are described in Table 1.

Liu Tungsheng (1917–2008) was a well-known Chinese geologist who made remarkable contributions to vertebrate paleontology, Quaternary geology, environmental geology and environmental science. He studied the Tibetan Plateau and the polar regions, and was known as the father of loess and the creator of loessology. In 1946, he began working at the central geological survey and initially followed Mr. Yang Zhongjian in vertebrate paleontology research. This work gradually exposed him to Quaternary geology, to which he formally changed his research interests when the academic focus in China switched to this area in 1956. Liu created the first specialized research institutions of Quaternary Geology in China (the Institute of Earth Environment and the Chinese Academy of Sciences) and trained 46 graduate students including five academicians (An Zhisheng, Liu Jiaqi, Ding Zhongli, Zhu Rixiang, and Guo Zhengtang).

As one of the founders of Chinese Quaternary and environmental geoscience, Liu Tungsheng created two Quaternary geology research institutions in China and trained a number of disciples in Quaternary research. He is the root of a quaternary academic pedigree that has prospered under the inheritance of Ding Zhongli, Guo Zhengtang, and the other researchers mentioned in 4.1. Table 2 lists the members of the Quaternary academic lineages descended from Liu Dongsheng. Data of Table 2 are from Liu Dongsheng's chronology and the Chinese Dissertation Database. The table refers to Liu Tungsheng as the first generation (abbreviated to 1G) member of the academic genealogy. The second generation (abbreviated to 2G) consists of 46 members including 10 post-doctoral researchers, 28 PhD students and 8 masters’ students. The third generation (abbreviated to 3G) consists of 217 disciples of 25 second-generation mentors. Data were taken from Quaternary research websites and China's database of published theses.

Academic fecundity directly quantifies the development of a genealogy, enabling comparison with the development and growth of the genealogy and a different genealogy.

There are 264 members in Liu Tungsheng's academic genealogy: one first-generation member, 46 second-generation members, and 217 third-generation members. Among the 25 mentors (at least) in the second generation, An Zhisheng, Zhu Rixiang, Liu Jiaqi, Guo Zhengtang, and Ding Zhongli have mentored 38, 25, 20, 20, and 19 disciples, respectively. These second-generation members formed their own genealogy branches. Including his disciples’ contribution to the academic genealogy, Liu Tungsheng's contribution to the academic genealogy was 154.5.

When measuring the academic influence forces index of an academic genealogy, we must investigate the individual academic influence of every member in the genealogy, namely, the improved h index (w index) of every member. To measure this indicator, we obtained the data of high-level papers published by the genealogy members from the Science Citation Index (SCI). The Web of Science™ Core Collection retrieves the surname (in full) and first name (abbreviated) of each member. The data are screened and cleaned based on the research areas or affiliations of the authors, then downloaded as full records.

For calculating the w indices of the genealogy members, we computed the weight coefficients on the free website established by Zhang (http://www.wcitation.org/). The w index requires five information parameters for each paper: No. (the serial number of the article), n (the total number of authors), k (the w index calculated by ranking the scholars in the article), cit (total number of citations), and cor (the position of the corresponding author in the list of names). The member data of the inner Liu Tungsheng academic genealogy were downloaded separately and the imported computing site automatically calculated the total and weighted citations of the different members, and hence the h and w indices of the members. For example, Liu Tungsheng's total citations and h index are 3,704 and 36 respectively, and his weighted total citations and w index are 1,181.45 and 20.05, respectively. The calculated academic influences forces of the separate generations and all generations are presented in Table 4.

From the numerical values in Table 4, we find that the third-generation influence has surpassed the second-generation influence. However, as the third-generation members are generally younger, their individual academic influences forces are not fully developed. Therefore, the average influence forces of individual members is only 1.67, far below that of second-generation members (7.57). In fact, the academic influence forces of different generations in the same genealogy cannot be simply compared, because the research hotspots of a certain field or research direction in different periods are greatly affected by the development of disciplines and national policies. Changes in research hotspots affect the citations of papers, thereby indirectly affecting intergenerational academic influence forces. But from the influence forces of different generations in Liu Dongsheng's pedigree, we can see from a macro perspective the process of this pedigree from inception to development to prosperity. In addition, when studying two different pedigrees of the same discipline at the same period, the intergenerational academic influence index J allows us to see the differences between the two pedigrees in different periods in more detail.

Because there are too disciples in the third-generation, and their individual academic influence forces are still relatively low, so we only display the academic influences forces of the first- and second-generation individuals and their contributions to the academic genealogy influence forces in Table 5. Second-generation members with outstanding academic influence forces are Guo Zhengtang, Sun Jimin, Ding Zhongli, Lv Houyuan, Zhu Rixiang, and An Zhisheng, their academic influence forces are 22.09, 21.59, 20.85, 21.87, 21.22, and 21.26 respectively. The collective academic influence forces of these six members exceed that of Liu Tungsheng. In a sense, higher academic influence means higher academic title, among them, An Zhisheng, Guo Zhengtang, Ding Zhongli, and Zhu Rixiang are academicians of the Chinese Academy of Sciences, and Lv Houyuan and Sun Jimin are candidates for academicians.

A scholar's contribution to the academic genealogy includes the academic influence forces of both the scholar and his or her disciples. As shown in Table 5, Li u Tungsheng's individual academic influence is 20.05, but his total contribution to the academic genealogy influence is 296.5. Similarly, the total influence contributions of Liu Jiaqi, Ding Zhongli, Zhu Rixiang, and An Zhisheng exceed their individual influences. Although the academic influences of Sun Jimin and Lv Houyuan are similar to those of Ding Zhongli and Guo Zhengtang, these researchers took few students, so the contributions of their disciples are not very significant.

Six members of the second generation of the academic genealogy (Guo Zhengtang, Sun Jimin, Ding Zhongli, Lv Houyuan, Zhu Rixiang, An Zhisheng) exerted higher individual academic influence than their mentor, Liu Tungsheng. This indicates that both the quantity and quality of their published papers are very high. However, Liu Tungsheng is more famous worldwide than his disciples. Therefore, the academic influence forces of different generations cannot be compared solely by the w value, as they also depend on the development speed of the subject in the generational period, social factors, and other influencers. The academic career of Liu Tungsheng was blighted by the 10-year Cultural Revolution, and his papers did not appear in international journals until 1981 (when Liu was 64 years old). In the 1990s, China's geology entered a period of rapid development, so the impact of his students influenced by the Cultural Revolution is relatively small. Consequently, the academic influence forces of scientists in different generations and specializing in different subjects are not directly comparable.

Liu Tungsheng's contribution to the academic genealogy is made up of his individual academic influence, half the academic influence of second-generation members, and one quarter of the academic influence of third-generation members. From Table 5, we find that Liu Tungsheng's individual academic influence is 20.05, whereas the academic contributions of his second-generation members sum to 552.9. Ultimately, Liu Tungsheng's contribution to academic genealogy reaches 296.5. Although the individual influence forces of the six prominent second-generation members are almost the same, their individual contributions to the academic genealogy differ widely. For instance, the individual academic influences of Guo Zhengtang and An Zhisheng are 22.09 and 21.26 respectively, and their total contributions to the academic genealogy influence are 51.39 and 62.42 respectively. Meanwhile, the individual academic influences of Sun Jimin, Ding Zhongli, Lv Houyuan, and Zhu Rixiang are almost 21, but their summed contributions to the academic genealogy are 29.97, 47.57, 24.66, and 33.04, respectively. Therefore, although the individual academic influences of these six members are very similar, their summed weighted influence forces are highest for An Zhisheng, followed by Guo Zhengtang, Zhu Rixiang, Sun Jimin, and Lv Houyuan. From the above discussion, we can see, the contribution of individual members to the academic influence forces of academic genealogy can better demonstrate a summed academic influence forces of a genealogy or branch, and also can demonstrate the ability of academic inheritance of individual members or a genealogy.