Statistical relationships between downloads and citations at the level of individual documents within a single journal
Statistical relationships between downloads and citations at the level of individual documents within a single journal
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DOI：
10.1002/asi.20200
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发表时间：
2005-08-01
影响因子：
--
通讯作者：
Moed, HF
中科院分区：
文献类型：
--
作者：
Moed, HF
检查从 ScienceDirect 下载的爱思唯尔电子期刊 Tetrahedron Letters 中的文档与科学信息研究所/汤姆森科学科学引文索引 (SCI) 处理的期刊中记录的这些文档的引用之间的统计关系。同步方法显示，下载和引用显示了所用材料的不同过时模式。前者可以通过由两个负指数函数之和组成的模型来充分描述，分别代表短暂因子和剩余因子，而后者的下降阶段符合简单的指数函数，其衰减常数在统计上与下载剩余因子的衰减常数相似。历时方法表明，随着一组文档的老化，其下载分布变得越来越倾斜，并且在统计上与其引文分布更加相似。提出了一种使用过时模式来估计引用对下载的影响的方法。研究发现，一篇文章被引用后的前 3 个月内，其下载量比该文章未被引用时的预期数字增加了 25%。此外，更多的施引文献下载导致了通过引用对被引文章的更多下载。对发表后 2 年内该期刊上 1,190 篇论文的分析显示，每 100 次下载就有大约 1 次引用。一篇文章的下载次数与 SCI 记录的引用率之间的 Spearman 等级相关系数为 0.22。当初始下载（定义为发布后前 3 个月内进行的下载）被丢弃时，相关性升至 0.35。然而，这两种结果都衡量了下载对引用的联合影响以及引用对下载的联合影响。将初始下载与后来的引用计数相关联，相关系数降至 0.11。研究结果表明，初始下载和引用与收集和处理相关科学信息过程中的不同阶段有关，最终导致期刊文章的发表。
Statistical relationships between downloads from ScienceDirect of documents in Elsevier's electronic journal Tetrahedron Letters and citations to these documents recorded in journals processed by the Institute for Scientific Information/Thomson Scientific for the Science Citation Index (SCI) are examined. A synchronous approach revealed that downloads and citations show different patterns of obsolescence of the used materials. The former can be adequately described by a model consisting of the sum of two negative exponential functions, representing an ephemeral and a residual factor, whereas the decline phase of the latter conforms to a simple exponential function with a decay constant statistically similar to that of the downloads residual factor. A diachronous approach showed that, as a cohort of documents grows older, its download distribution becomes more and more skewed, and more statistically similar to its citation distribution. A method is proposed to estimate the effect of citations upon downloads using obsolescence patterns. It was found that during the first 3 months after an article is cited, its number of downloads increased 25% compared to what one would expect this number to be if the article had not been cited. Moreover, more downloads of citing documents led to more downloads of the cited article through the citation. An analysis of 1,190 papers in the journal during a time interval of 2 years after publication date revealed that there is about one citation for every 100 downloads. A Spearman rank correlation coefficient of 0.22 was found between the number of times an article was downloaded and its citation rate recorded in the SCI. When initial down loads-defined as downloads made during the first 3 months after publication-were discarded, the correlation raised to 0.35. However, both outcomes measure the joint effect of downloads upon citation and that of citation upon downloads. Correlating initial downloads to later citation counts, the correlation coefficient drops to 0.11. Findings suggest that initial downloads and citations relate to distinct phases in the process of collecting and processing relevant scientific information that eventually leads to the publication of a journal article.