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Expected impact index
Definition
The two-year expected impact index (expressed as a positive number) is defined as:
The share of expected citations of the publications of an actor (institution, country, etc.) over a given period of time (for example 2 years) and within a given frame of reference (world for example) proportional to the share of these publications in the same frame of reference.
The expected impact takes into specific account the impact of the journals in which the actor's publications appear. It is equivalent to the relative impact that an actor would obtain if in each of the journals where its articles are published these articles received the average of citations received for all articles published in the journal.
N.B. The expected impact index is normalised; therefore at the scale of the frame of reference this indicator is equal to 1. When the indicator is greater than 1, the actor enjoys a greater expected visibility than the average for the frame of reference (or less than average if the indicator is less than 1).
Example
Expected impact index and relative citation rate (RCR) for publications of institution X at the world level by scientific field in fractional count (2002, 2003).
- Click to enlarge (taken from a bibliometric performance report)
Interpretation: In 2003 the expected visibility of institution X was greater than the world average in fundamental biology and in biomedicine with expected impact indexes in 2003 of 1.40 and 2.25 respectively.