  The two most used citation impact indicators in the assessment of scientific
journals are, nowadays, the impact factor and the h-index. However, both
indicators are not field normalized (vary heavily depending on the scientific
category) which makes them incomparable between categories. Furthermore, the
impact factor is not robust to the presence of articles with a large number of
citations, while the h-index depends on the journal size. These limitations are
very important when comparing journals of different sizes and categories. An
alternative citation impact indicator is the percentage of highly cited
articles in a journal. This measure is field normalized (comparable between
scientific categories), independent of the journal size and also robust to the
presence of articles with a high number of citations. This paper empirically
compares this indicator with the impact factor and the h-index, considering
different time windows and citation percentiles (levels of citation for
considering an article as highly cited compared to others in the same year and
category).
