**2.2. Tension between altmetrics and bibliometrics**

To date, web-based impact in social media has been measured mainly by the number of downloads or clicks, or by using indicators created by the operators themselves, such as ResearchGate's (RG) score [5]. These web-based metrics get the umbrella term "alternative metrics," or "altmetrics" [6]. Collecting and analyzing altmetrics is gaining relevance, and not only in science. Political decision makers, too, are attaching corresponding importance to the issue. Thus, the German Federal Ministry of Education and Research (BMBF), for example, has launched the first study evaluating the possibilities and limitations of using altmetrics for impact measurements [7]. Furthermore, BMBF has initiated a funding line for quantitative

science research, in which the further investigation of altmetrics plays a central role.

using altmetrics and provide information on prospects for success.

**2. Scientific discussion of altmetrics**

**2.1. Basic scientific context of altmetrics**

124 Scientometrics

The present chapter gives an overview of the current stance of scientometric research on altmetrics. We show example metrics and discuss what conclusions can be drawn from them. It will become apparent that altmetrics do not meet the expectation of measuring scientific impact because the data are too heterogeneous, their interpretation has not yet been sufficiently clarified, and an indicator system with meaningful and reliable benchmarks does not yet exist. Furthermore, we will investigate what strategies scientific institutions can pursue in

The introduction of alternative indicators for the quantification of scientific output and the associated resonance on the Internet can be traced back to a discussion by Priem et al. in 2010 [6]. They questioned whether focusing on the classical bibliometric indicators adequately reflects the scientific and social significance of research in the era of the Internet. During the course of this discussion, the expression "altmetrics" was coined as a collective term for alternative metrics, which include web-based information on scientific publications. Therefore, altmetrics can be regarded as a complement to classical bibliometric indicators providing new information that was previously unavailable, predominantly from the social media sector. This new information makes it possible to examine the reception of scientific publications, for

example, on news sites, in science blogs, policy papers, and other web-based sources.

The altmetrics community can now look back on almost 7 years of research. On the one hand, the "visibility and presence of altmetrics are quite impressive" [8] because they are used as marketing tools by many scientific publishers, more than 300 publications on the subject have appeared, and there are even conferences dedicated solely to altmetrics. On the other hand, there is no uniform definition, and therefore no consensus on what exactly is measured by altmetrics and what conclusions can be drawn from the results [8–10]. The only consensus regarding the term definition is that the indicators discussed are intended to measure the attention paid to scientific output where bibliometrics reaches its limits—that is, on the Internet [6]. There is, however, a lack of any further and more detailed differentiation of such metrics.

Due to the fact that the base communities are the same, there is a certain tension between altmetrics and bibliometrics. Both (sub-)disciplines are intended to fulfill the same purpose, to generate a picture of scientific impact, but based on different influencing factors. Almost like a reflex, the two fields are often set in relation to each other, compared, or set up as an either/or selection.

In contrast, within the community itself, there is a general consensus that both disciplines complement each other instead of one excluding the other [11]. Altmetrics are not intended to replace the peer review process or bibliometrics; rather, they should be viewed as a second opinion [10] and a "new perspective on communication by and about science in social media" [7]. A report by the expert group on altmetrics on behalf of the European commission also argues for classical bibliometrics that they "offer complementary approaches to evaluation" together with alternative metrics [12]. The expert group furthermore sees potentials for including a wider audience beyond the closed science system and for collecting information considerably faster than with conventional metrics. Furthermore, the idea of this approach is not limited to conventional scientific publication formats but offers the perspective of making data sources such as software and data sets accessible (e.g., as part of research data management).

The big difference between bibliometrics and altmetrics is the aspect that scientific publications are the traditional and indispensable main output of science. Thus, bibliometrics measures something that is at the center of the scientific reward system. The communication of science to society—that is, what is measured by altmetrics—is not part of the scientific reward system as yet. Creating incentives and expanding this reward system at this point would likely lead to increased use of social media by science and thus also strengthen altmetrics.
