|Year||Source-Normalized Impact per Paper (SNIP)||# Citations||# Articles||Impact per Publication (IPP)||Database Citation Potential (DCP)|
The Source-Normalized Impact per Paper (SNIP) measures the contextual citation impact by weighting citations based on the total number of citations within a subject field. This unique perspective enables direct comparison of journals in different subject areas. The impact of a single citation is given a higher value in subject areas where citations are less likely, and a lower value in subject areas where citations are more likely.
The SNIP is a ratio between a journal's Impact per Publication (IPP) as the numerator and its Database Citation Potential (DCP) as the denominator (i.e. SNIP = IPP/DCP). The IPP is simply the average number of citations received in a particular year (e.g. 2018) by papers published in the journal during the three preceding years (e.g. 2015, 2016 & 2017). For the denominator, we know that there are large differences between scientific fields in the frequency at which authors cite articles. In view of this, for each journal an indicator is calculated of the citation potential within the subject area it covers. This citation potential is represented by the DCP score.
The Source-Normalized Impact per Paper enables a direct comparison of journals in different subject fields. Citation potential is shown to vary, not only between journal subject categories (i.e. groups of journals sharing a research field) or disciplines (e.g. journals in Mathematics tend to have lower values than journals in the Life Sciences), but also between journals within the same subject category. For example, theoretical journals tend to show higher citation potentials than applied or clinical journals. Likewise, journals covering emerging topics tend to have a higher citation potential than journals in classical subjects or more general journals.
The SNIP value helps authors to identify which journals are performing best within their subject field, thereby helping them to decide where to publish. Note that the Source-Normalized Impact per Paper is calculated using data from the Scopus database.