The Research Production of Nations and Departments: A Statistical Model for the Share of Publications

TL;DR

This paper introduces a statistical model to analyze the share of research publications produced by countries or institutions, accounting for randomness and enabling better interpretation of differences over time.

Contribution

It presents a simple probabilistic model for research output shares, with methods to calculate confidence limits and assess underlying production capabilities.

Findings

Model fits well with data from 36 journals (1996-2016).

Analysis of 26 subject categories supports the model's validity.

Highlights importance of consistent subject coverage.

Abstract

Policy makers and managers sometimes assess the share of research produced by a group (country, department, institution). This takes the form of the percentage of publications in a journal, field or broad area that has been published by the group. This quantity is affected by essentially random influences that obscure underlying changes over time and differences between groups. A model of research production is needed to help identify whether differences between two shares indicate underlying differences. This article introduces a simple production model for indicators that report the share of the world's output in a journal or subject category, assuming that every new article has the same probability to be authored by a given group. With this assumption, confidence limits can be calculated for the underlying production capability (i.e., probability to publish). The results of a time series analysis of national contributions to 36 large monodisciplinary journals 1996-2016 are broadly consistent with this hypothesis. Follow up tests of countries and institutions in 26 Scopus subject categories support the conclusions but highlight the importance of ensuring consistent subject category coverage.