Tony Hirst

Tony Hirst is working part time for the School of Data as our Data Storyteller, shaping the materials, masterminding the blog and running workshops. Tony is also a Lecturer in the Department of Communication and Systems at The Open University, Visiting Senior Fellow in Networked Teaching and Learning at the University of Lincoln, and regular blogger at OUseful.info.

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  • Elijah Meeks What I was trying to do in this post was just show a very quick way of getting started using Gephi and some of the tools available within it, without trying to put in too many caveats for now! For example, care needs to be taken when reading meaning into the layout of nodes under the Force Atlas2 algorithm, and when interpreting false colour groupings based on modularity class assignment. (Choosing particular colours for groups can also be fraught with false or mis-presumed interpretations…)

    I should maybe have stressed a little more the way in which I use network tools and layouts as a mapping technique within an ongoing conversation with a data set, using the results of one view to inform the asking of further, more refined, questions of the data, treating each view as containing “no truth-many truths” dependent on the way a question is phrased and asked of the data (for example, based on the data itself and how it was collected, the filters applied to it, the statistics and mappings used to generate a particular view, and so on.)

    In the current example, the modularity clusterings are used as much as anything to colour the map and encourage the reader to look for associations. The weak effect in this case might actually be useful as a warning to reading false meaning into the machine suggested decomposition. In future posts, I’ll try to find networks with better cluster definition and contrast them with this one. If you want to explore some of the networks around other groups, I can let you have the data…

    • Tony (I assume), I just meant to raise a cautionary flag. It’s obvious by the content of the post that you’re trying to ground folks in the basic principles of using Gephi, which I wholeheartedly support. It’s just that I’ve reviewed a string of papers recently where folks use the community detection algorithm in Gephi out-of-the-box and don’t know what a modularity score is and how it affects their results. Keep up the good work!

  • A modularity score of .24 means there is not a statistically significant community signature, and thus should not be used unless a domain expert can argue that in this case such a low score merits attention.

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