Normalised citation score
The normalised citation score for an articles takes into account the average number of citations received by all articles in the same subject field as the article of interest, published in the same year.
The reason for comparing the article to other articles in the same field is because different disciplines have different citation levels.
The reason for comparing the article to other articles published in the same year is because older articles have had longer to accrue citations than more recently published articles have.
This can be illustrated by looking at a couple of articles by Mark Greenberg, a consulting professor in the School of Education, Environment and Development, both published in 2011.
One of these articles was published in the Journal of Experimental Child Psychology, and so is categorised by Scopus as being in the field of Experimental and Cognitive Psychology.
The other one was published in the journal First Language, and so is categorised by Scopus as being in the field of Language and Linguistics.
|Experimental and Cognitive Psychology||Language and Linguistics|
|B.L. Rhoades, M.T. Greenberg, S.T. Lanza and C. Blair, 'Demographic and familial predictors of early executive function development: Contribution of a person-centered perspective'. Journal of Experimental Child Psychology 108 (3) 2011. 638-662||K.E. Nelson, J.A. Welsh, E.M.V. Trup and M.T. Greenberg, 'Language delays of impoverished preschool children in relation to early academic and emotion recognition skills'. First Language 31 (2) 2011. 164-194|
|Total citations = 11||Total citations = 5|
|Mean citations received by 2011 articles in this field = 1.91||Mean citations received by 2011 articles in field = 0.35|
Normalised citation score = 11/1.91 = 5.76
Normalised citation score = 5/0.35 = 14.3
As the table shows, the article on the left has received more than twice as many citations as the article on the right.
However, the table also shows that the field of Experimental and Cognitive Psychology generally has much higher citation levels than the field of Language and Linguistics.
This means that the article on the right is actually the one with the higher normalised citation score, even though it has received fewer citations.
The other main way of assessing the citation performance of a particular article is in terms of its percentile position. Like the normalised citation score, this takes into account the citation performance of other articles in the same field published in the same year.
This works by imagining that all the articles published in the same subject in the same year are listed in order from most cited to least cited, and seeing where this particular article comes in the list.
Thus, for example, 6,158 articles in Language and Linguistics were published in 2011.
Most-cited 1% (62 articles) received 7 or more citations
Most-cited 5% (308 articles) received 3 or more citations
Most-cited 10% (616 articles) received 2 or more citations
The article 'Language delays of impoverished preschool children in relation to early academic and emotion recognition skills' has received 5 citations at time of writing.
This is not enough to put it in the most-cited 1% in its field, but is enough to put it in the most-cited 5% in its field.