This is the data arising from counting or recording the way academic papers reference each other. It is a form of network data where papers are linked in a directional way as one paper cites another. A simple metric of this is the citation count, the number of times a paper has been cited by others. However, it is important to note that, in common with other forms of network data, the citation count usually follows a power law with a long tail and is not suitable for tests and analysis that rely on the data being approximately Normal.
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