Terminology and Indicators

Terminology

• Normalization. To compare like with like. For example does field normalization mean that you compare the number of citations to a researcher's articles in a subject area with the world average for articles in the same subject area. You can also normalize on a journals basis. This means that you compare the number of citations to an article to the average number of citations to the articles in the same journal and year. Normalization to article type is also important in bibliometrics.
• Fractionalization. A method that compensates for the number of authors of a publication so that only a part of the publication is attributed to the unit in question. This is considered more fair when an article has many authors. You can also fractionalize against institutions and countries.
• Self-citations. If an author to an article appears in the author list of a cited article. The fraction of self citations are relatively constant and can often be ignored if larger data sets are analyzed.

Indicators

Bibliometrics uses different indicators to compare different authors, institutions or countries.
Some examples of indicators:

• The number of published items during a time period
• The number of published items per researcher (or employee) in a group during a time period
• The number of citations during a time period.
• The number of citations per researcher (or employee) in a group during a time period
• The number of citations per item during a time period.
• Field normalized citation score (the crown indicator). The number of citations during a time period divided with the world average in the same subject area and time period. Is given as a decimal number with the world average as 1.
• Top 5%. The share of published items among the 5% most cited items in the same subject area and time period. 
• H-index. H-index for an author is the number of publications (h) from the author cited at least h times. For example 10 articles each cited at least 10 times gives a h-index 10.