The aim of this article is to develop new patent indicators for evaluating technological innovation competitiveness between companies. A novel indicator representing an industrial's patent performance, Essential Patent Index (EPI), was developed by incorporating information on who cited these patents and when these patents were cited, based on the assumption that both contribute to meaningful quality assessment. By combining EPI and Chi's well known Technological Strength (TS) indicator, a second novel indicator Essential Technological Strength (ETS) was developed to represent the innovation competitiveness of an individual company. In this study, patent performance of three high-tech industries in Taiwan were analyzed using ETS as well as the traditional TS for comparison. Results from this analysis demonstrated that ETS provided better insights by clearly verifying the latent influence of citations, reinforcing the impact of essential patents, and aggrandizing the differences of innovation competitiveness between companies.

Purpose -The purpose of this research is to investigate the relationship between journal self-citation and journal impact factor ( JIF)/journal immediacy index ( JII). Design/methodology/approach -This research examined research papers in 20 key journals in environmental engineering with a publication year range of 1999 to 2008. The bibliographical information of cited references was obtained from the Science Citation Index Expanded of the Web of Science. Findings -The findings indicated that JIF and JII values changed only slightly regardless of the inclusion or exclusion of self-citations, suggesting that the influence of self-citation on journals was insignificant. Consequently there is no need for evaluations to exclude journal self-citations in journal or researcher evaluations. In addition the findings indicated that JIF and five-year JIF were highly correlated, suggesting that it would not be necessary to extend the calculation of JIF to five years. Considering the cost in terms of time and effort, the two-year JIF is sufficient in the discipline of environmental engineering. Originality/value -This research provides a better understanding of journal self-citations in journal or researcher evaluation with JIF and JII as indicators.

This paper attempts to identify the relationship between co-authorship and the currency of the references and author self-citations in the key journals of environmental engineering. The results show that the self-citation rate of co-authored articles is higher than in single-authored articles. A statistically significant correlation is identified between the numbers of co-authors, the rate of author self-citing and the author self-cited; though it was a low correlation. The value of coefficient correlation between the number of co-authors and the author self-citing rate is slightly higher than that between the number of co-authors and the author self-cited rate, which indicates that the number of co-authors hold a stronger correlation with the self-citing rate than the self-cited rate. Meanwhile, self-citing references are found to be more up-to-date than references to others. The range of publication years of self-citing references is smaller than that of references to others, indicating that researchers tend to preferentially cite their own recent works. There is no significant difference in the latest references between self-citing references and the references to others. It might result from electronic journals that provide an easy access to the most current publications.

This study evaluates the impact of author self-citations on h index by exploring 583 authors whose works appear in key periodicals in environmental engineering. The findings show that authors’ h values have high correlation with authors’ article number, total cited count, and their rankings. There is also a high correlation with h index values and rankings of h values. The study indicates that self-citations have little impact on the values of h index and the h index rankings, whether or not articles with authors’ self-citation are included. Further investigations reveal that, for authors with high values in h index, the two h index values are both highly correlated and with significant difference either with self-citations or without. A similar pattern is seen in authors with low h values. The results suggest that there is no need to deliberately exclude self-citations in analysing or evaluating research performance in environmental engineering.

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