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The effect of academic inbreeding on scientific effectiveness


In academia, the term “inbreeding” refers to a situation wherein PhDs are employed in the very same institution that trained them during their doctoral studies. Academic inbreeding has a negative perception on the account that it damages both scientific effectiveness and productivity. In this article, the effect of inbreeding on scientific effectiveness is investigated through a case study. This problem is addressed by utilizing Hirsch index as a reliable metric of an academic’s scientific productivity. Utilizing the dataset, constructed with academic performance indicators of individuals from the Mechanical and Aeronautical Engineering Departments, of the Turkish Technical Universities, we demonstrate that academic inbreeding has a negative impact on apparent scientific effectiveness through a negative binomial model. This model appears to be the most suitable one for the dataset which is a type of count data. We report chi-square statistics and likelihood ratio test for the parameter alpha. According to the chi-square statistics the model is significant as a whole. The incidence rate ratio for the variable “inbreeding” is estimated to be 0.11 and this ratio tells that, holding all the other factors constant, for the inbred faculty, the h-index is about 89% lower when compared to the non-inbred faculty. Furthermore, there exists negative and statistically significant correlation with an individual’s productivity and the percentage of inbred faculty members at the very same department. Excessive practice of inbreeding adversely affects the overall productivity. Decision makers are urged to limit this practice to a minimum in order to foster a vibrant research environment. Furthermore, it is also found that scientific productivity of an individual decreases towards the end of his scientific career.

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  1. 1.

    Similar results are obtained when only mechanical engineering departments are considered.

  2. 2.

    Model is estimated also by using only rank specific, only department specific and non-specific (pooled data).

  3. 3.

    We would like to acknowledge the anonymous reviewer for pointing out this issue.


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Correspondence to Onur Tuncer.

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Inanc, O., Tuncer, O. The effect of academic inbreeding on scientific effectiveness. Scientometrics 88, 885–898 (2011).

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  • Academic inbreeding
  • Scientific effectiveness
  • Turkish universities