Which one of the following is an indication of the quality of a research…
2012
Which one of the following is an indication of the quality of a research journal ?
Answer: A. Impact factor — Concept: Bibliometric indicators are not interchangeable, because each one is defined over a particular unit. A journal-level indicator is computed from the…
- A.
Impact factor
- B.
h-index
- C.
g-index
- D.
i10-index
Show answer & explanation
Correct answer: A
Concept: Bibliometric indicators are not interchangeable, because each one is defined over a particular unit. A journal-level indicator is computed from the articles of a single title and therefore describes that title. An author-level indicator is computed from the publication set of a single researcher and therefore describes that person’s output. So the first question to ask of any metric is: whose citations does it aggregate, and over what unit?
Application: The unit being judged here is a research journal, so the indicator must be one that is defined on a journal. The impact factor is exactly that. In Journal Citation Reports, a title’s impact factor for a year is the number of citations recorded in that year to the items the title published in the two preceding years, divided by the number of citable items it published in those same two years. Both the numerator and the denominator are drawn from that one title, so the value belongs to the journal itself, and a higher value means the journal’s recent articles are being cited more often. That is why the impact factor is the standard indication of a research journal’s quality. The answer is the impact factor.
Contrast: The other three indicators were introduced to characterise the output of an individual researcher, and that is how they are conventionally reported:
Indicator | Conventionally reported for | Definition |
|---|---|---|
h-index | A researcher’s publication set | The largest h for which h publications have each received at least h citations (Hirsch, 2005) |
g-index | A researcher’s publication set | The largest g for which the g most-cited publications together have at least g2 citations, i.e. g times g (Egghe, 2006) |
i10-index | A Google Scholar profile | The count of publications with at least 10 citations each (Google Scholar, 2011) |
Cross-check: Be precise about the limits of that contrast. The h-index and the g-index are formulas that can be applied to any set of documents, and h-indices are in fact also published at journal and publication level — Google Scholar Metrics reports one for every publication it ranks. What sets the impact factor apart is that it is defined for a journal and for nothing else: it has no author-level reading at all. So among the four indicators offered, the impact factor is the one whose whole purpose is to indicate the standing of a research journal, and the official answer key for this UGC NET paper records it as the single accepted answer.