Interpretation of Academic Journal Impact Index (AJCI)
1. Definition of the influence of academic journals
Generally speaking, the influence of academic journals (hereinafter referred to as "journals") generally refers to the ability of journals to publish academic research results in a certain period of time and promote the development of related academic research and applications in a certain period of time. This ability comes from the academic value and application value of literature, but it is also restricted by many factors, such as the degree of social recognition and recognition of its value, the diversity of journal content, the dissemination and diffusion ability of the journal itself and related channels, etc. Therefore, it is very complicated and difficult to make an objective and accurate qualitative analysis and evaluation.
Ignoring the qualitative difference of academic influence of different documents, we can reflect the influence of journals in a statistical year by measuring the number of times journals published by some source documents are cited. Simple and commonly used measurement indicators include total cited frequency (TC, extension, the evaluation object is all the published documents in this journal), impact factors (if the evaluation object is the documents published in the first two years of the statistical year), that is, annual indicators (intensity, the evaluation object is the documents published in the statistical year) and so on.
Obviously, the evaluation object of the above indicators is the literature published by periodicals in different periods, and the evaluation angle and measurement method are different, so any indicator can not fully reflect the influence of periodicals. One-sided emphasis on one of the indicators in periodical evaluation will lead to one-sided development tendency of periodicals, even lead to academic misconduct of periodicals and interfere with the normal development of periodicals. Therefore, people have been hoping to find a comprehensive index to reflect the influence of periodicals. However, in the past, the work in this field always tried to assume TC, IF and other indicators as additive scalars in the same linear space a priori, and to synthesize a "comprehensive indicator" according to a set of artificially set weight parameters, without paying attention to distinguishing the inherent attributes of these indicators, so it was difficult to give a reasonable explanation for the periodic ranking results.
In 20 13, China Scientific Literature Metrological Evaluation Research Center put forward a comprehensive evaluation method for the influence of academic journals, which was applied to the selection of "China's most internationally influential academic journals" for two consecutive years. Its basic principle, calculation method and results have been basically recognized by academic and periodical circles at home and abroad.
2. Basic definition of journal impact index
Definition 1: the ranking space of journal influence
If tc and IF are normalized to TC and IF of comparable journals in a certain range (within the same discipline) respectively, and journals are sorted according to their size, then TC and IF can be mapped to a two-dimensional space in the sense of sorting, which is called "journal influence sorting space". Since tc and if are independent of each other in the sense of ordering, tc and if are orthogonal.
Definition 2: Equidistant lines of periodic influence
Definition 3: Journal Impact Index (CI)
CI is a comprehensive index reflecting the influence of each periodical in a group of periodicals.
Index (index) is a numerical value calculated by the vector of total cited frequency (TC) and impact factor (IF) in a statistical year, which is used to rank a group of journals.
The calculation formula of CI is:
The geometric meaning of CI is as follows:
Figure 1 Schematic Diagram of Journal Impact Index CI
As shown in figure 1, (0,0) indicates journals with zero impact factor and total cited frequency. The dots in the upper right corner (1, 1) represent the "most influential journals" with the largest impact factors and total cited frequency in this group. Draw an arc with (1, 1) as the origin. The arc is the equipotential line of the influence line, and each point on the arc represents the journal with equal CI value. The relative influence of the journal corresponding to the point distributed at the lower left of the arc is smaller than that of the journal distributed at the right of the arc. It can be seen vividly that the greater the CI value of a periodical, the smaller the gap between the periodical and the "most influential periodical" in the group.
3.3. Specific statistical methods. Cochlear implant
3. 1 statistical source literature
In order to highlight the influence of journals on mid-to-high-end academic research, when calculating TC and IF that constitute CI, the top 60% journals in the Annual Report of China Academic Journals (20 15 Edition), as well as doctoral dissertations and conference dissertations, excluding master's dissertations, are selected.
3.2 Other citation frequencies In order to reflect fair measurement, in CI calculation, TC is the total other citation frequency, and IF is the influence factor of other citations.
3.3 Log Quality Index (JMI) From the schematic diagram of CI, it can be seen that the bit lines such as CI have a good inhibitory effect on the general singular behavior of a single index.
However, for special strange phenomena, especially in the case of blindly expanding the number of papers and reducing the academic quality in pursuit of big TC, the inhibition effect is not ideal, which interferes with the fairness of CI ranking. In order to solve this problem, we introduce the dose-effect index (JMI) to eliminate the impact of this singularity. Dose effect index (JMI) is the ratio of the number of articles corresponding to the journal impact factor to the journal impact factor, that is, the number of articles required for the journal unit impact factor. Defined as:
The bigger the JMI, the more "bloated" the journal is, that is, the scale of the journal is large and the benefits are not high. In order to fully reflect the quantity-effect relationship of journals, JMI adopts the comprehensive impact factors published in the annual report (20 15 edition).
3.4JMI's revision of CI
The annual report (version 20 15) ranks the self-developed and social science journals from JMI to JMI. According to this ranking, the list of the top 5% journals with more citable documents than the average citable documents is selected as the list of journals that need to revise CI, and the TC weight of these journals is revised, while other journals are not adjusted. The weight ratio of TC and IF in CI is 1: 1, and the adjusted journal TC weight is reduced to 0.2~0.05 according to JMI size. Specific adjustment measures are as follows:
Where k is the adjustment coefficient of other reference frequencies. Journals are divided into three grades according to the size of JMI, and the TC weight adjustment coefficient is the ratio of the average JMI of this journal to the average JMI of all journals. The specific data of the corresponding weights of JMI indicators in each file are as follows: table 1 JMI type and other cited frequency adjustment factors.
JMI type
Value interval
Adjustment coefficient of other reference frequencies (K)
Adjust the number of periodicals
agency
heavy
[ 10000~20000)
0.2
43
The branch of academic or vocational research.
Very bloated
[20000~40000)
0. 1
23
Extremely bloated
≧40000
0.05
1 1
oneself
heavy
[7000~ 17000)
0.2
102
The branch of academic or vocational research.
Very bloated
[ 17000~37000)
0. 1
40
Extremely bloated
≧37000
0.05
15
4. Description and discussion
We introduce an index CI which can comprehensively reflect the academic influence of journals, and can rank the influence of journals in a certain discipline, but it cannot be directly used to evaluate the quality of journals. It should also be noted that CI is defined within a group of journals, and can only be used for ranking journals within the group, and cannot be compared across groups. If cross-group comparison is needed, different groups should be defined as one group and the CI value should be recalculated.
In this report, JMI revised the competitive intelligence of 234 journals. If there is anything wrong, please criticize and correct me.
In the definition of CI, only TC and IF are used, and other measurement indexes, such as annual index and citation half-life, are not considered. There are still some problems to be discussed. Further research is still in progress, and relevant experts are invited to make valuable suggestions.