This category contains 20 posts

Current events for Beth’s class

Beth Chalecki asked me to give a talk on cyber security for her course at Boston College. While I won’t post the slide deck here, I will compile a reading list on the blog. I’d like to note that the blogroll at right includes several of the big names in the field: Bruce Schneier, C. … Continue reading

My blog doesn’t depress wages

I’m going to go out on a limb here and say Paul Bradshaw is wrong. The argument goes like this: drive up the supply of journalists, drive down the unit price of a story. Sounds fine, until you think through the argument more carefully. It only matters that hacks bloggers are giving away drivel content … Continue reading

Full hearing: US Senate on Cyber War Readiness

Highlights from the US Senate panel on cybersecurity 23 February 2010. Mary Ann Davidson, CSO (Oracle). Required reading! Ms. Davidson masters the subject in bright prose. This is an excellent indictment of the rush deploy smart grid technologies before we’ve had time to harden them from the types of attacks that routinely take computers off … Continue reading

Export Trade Clusters

This post, as with the prior ones on trade clusters, aims to help visualize patterns of trade in the OECD from 50 years of partner trade statistics. The data is rich, meaning we should be able to develop rich intuition by exploring it visually. These slides follow the method laid out in Jong-Eun Lee, “Two … Continue reading

Visualizing Dyadic Trade Flows

I gave a talk at the Fletcher School today on my work on dyadic trade flows (slides). In a nutshell, the talk argues that cartograms and dendrograms can give students and practitioners a better understanding of the patterns of trade among partner contries, both for teaching and for research. We have thousands of observations of … Continue reading

Unilateral trade clusters using raw import flows

This set of dendrograms, again, is based on raw partner import flows from OECD. The dendrograms show complete linkages (all countries in a cluster exceed the threshold value for mutual trade flows), but the dyad is measured by the greater of the two trade flows. This gallery shows an annual series of dendrograms using that … Continue reading

Bilateral import clusters using raw trade flows

As promised, here are a new round of dendrograms using OECD trade data as a reciprocal distance measure among countries reporting. In trade, relationships matter, and these dendrograms show which relationships matter the most. Clusters are drawn by complete linkages, using the lesser of the two pairwise trade flows (greater notional distance). The important thing … Continue reading

Unilateral import clusters in international trade

As with yesterday, these graphics depict complete clusterings in international trade, treating the partner country’s share of total home country imports as a raw distance measure. The greater the share, the closer the two countries are. For visual clarity, I have used logarithmic scales; so the scale at left doesn’t have any concrete meaning. The … Continue reading

Bilateral import clusters in international trade: insights

Major insights from the dendrograms in the previous post: Among OECD countries, New Zealand and Australia cleave closest to the Pacific alliance: NAFTA, Japan and Korea. Scandinavian countries have undergone a durable shift in trade patterns, away from France and the Iberian peninsula, and toward the British Isles. Greece, Italy, and Turkey constitute a durable … Continue reading

Bilateral import clusters in international trade

One big problem in the visualization of bilateral statistics is that maps don’t work very well. Dendrograms give a very attractive and intuitive solution to the problem by dispensing with geographic information altogether. The dendrogram shows how clusters of countries form along a continuum of closeness. For international trade, I’ve presented below a cluster analysis … Continue reading


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