Posts Tagged networks

What’s ahead in 2010? Shaun Hendy Dec 29

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2010 is shaping up to be a defining year for New Zealand’s RS&T system. We will be hearing how the Government will set its RS&T priorities and what these priorities will be. The CRI task force will be reporting back, and we will find out how the Government is going to encourage R&D in the business sector. As I discussed in a post last month, the money spent by the business sector on R&D is strongly correlated with patenting.

What will I be blogging about in 2010? I have devoted quite a bit of time this year discussing data that we have extracted from the OECD patent database. There is still a lot of information to be mined from this database and I will be continuing to discuss this in the New Year. For instance, I will have more to say about inventor networks and how their structure changes with network size. I also want to look at some specific networks in more detail, comparing their size and structure between countries.

I will also follow up on some of my earlier posts on bibliometrics. It took me a while to get permission from Thompson Reuters to start publishing citation data, but this has now come through, so I will be looking at how the impact factors of New Zealand institutions have changed over the last 20 years. I also want to follow up with more detail on the surprisingly large co-author networks that exist within the New Zealand science community.

Of course, from time to time, I will blog on other matters that interest me throughout the year. I have been following the progress of some new types of collaborative research: mathematicians have been learning how to use the mass collaboration that blogging allows to prove theorems and solve original research problems. This is, after all, the reason that the web was created in the first place.

Collaboration, whether through blogs or other means, may be the key to New Zealand taking its own R&D to scale.

In the meantime, I hope you are all enjoying your holidays!

The University co-author network Shaun Hendy Oct 27

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Uni coauthor networkIn an earlier post I looked at the 2008 CRI co-author network. Now let’s turn to the University network. Using the Thomp­son Reuters Web of Sci­ence again, I found 5116 publications in 2008 with authors from New Zealand universities. In total 13930 authors contributed to these papers. The network is shown on the right.

Again, a remarkably large fraction of authors belong to the giant component. In the 2008 CRI co-author network, 2325 of the of the 4496 authors belonged to the largest connected component. Here, 9771 of the 13930 authors belong to the largest component – that’s a remarkable 70%.

We can make some other comparisons between the CRI  and the university networks. In the university network, on average each author has 8.4 collaborators; in the CRI network, each author has 5.1 collaborators. Apparently, university authors are more collaborative.

Degree distribution However, just comparing the average numbers of co-authors is misleading. I’ve graphed the distribution of co-author numbers for the universities and the CRIs on the left i.e. the proportion of authors with certain numbers of co-authors. From the graph it’s apparent that the difference between the university and CRI networks lie in the tails of the distributions. There are a number of university authors that participate in very large collaborations. For instance, there are a dozen or so authors in the network whose only published work in 2008 was one with 343 co-authors. Big science!

It is probably not surprising that university researchers are more likely than those in a CRI to participate in very large overseas collaborations. This skews the average number of co-authors for university researchers relative to CRI researchers, making the mean number of co-authors larger.

The CRI co-author network Shaun Hendy Oct 19

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CRI coauthor network To what extent do scientists at Crown Research Institutes (CRIs) collaborate? Using the Thompson Reuters Web of Science, I have constructed the CRI co-author network for 2008. As best I can determine, the Web of Science database contains 1271 papers from 2008 with CRI authors. In total, 4496 authors contributed to this set of papers – not all these authors are from CRIs of course, but they have all co-authored a paper with someone from a CRI. The network is shown on the left: the green dots are authors, with blue links between pairs of authors indicating co-authorship on at least one paper.

What surprises me is the extent of the largest  set of authors that can be connected to each other by co-authorship. This largest connected component can be seen sitting in the centre of the 2008 network diagram, containing 2325 of the of the 4496 authors (52%). It contains authors from many of the CRIs (including me and a number of my colleagues at IRL) and from a number of Universities, both in New Zealand (including many from the the MacDiarmid Institute) and overseas. The next largest connected component contains only 31 authors.

Connected component If you look at the size of the largest connected component in the CRI co-author networks each year, 2008 is the largest. Just after the CRIs were established, in 1994,  the largest component contained only 195 authors, occupying only 12% of the network. One reason for the growth of the largest component is that since 1994, the average number of co-authors each author has in a given year has risen from two to five. In other words, CRI scientists are collaborating more extensively in 2008 than they were in 1994.

2degrees? Shaun Hendy Sep 30

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A new mobile phone network called “2degrees” was launched in New Zealand earlier this year. As explained in its advertising campaign (fronted by the excellent Rhys Darby from Flight of the Conchords), the name alludes to the (alleged) only two degrees of separation between New Zealanders, as opposed to the six degrees that separate the rest of the world. Are Kiwis really so well connected?

The idea that people are separated socially from one another by at most six degrees has been around for a hundred years or so. Psychologist Stanley Milgram put it to the test in the late 1960s, using a chain-letter approach to delivering mail. Rather than addressing the letter directly to the intended recipient, Milgram sent the letter to a randomly selected intermediate, giving them the final recipient’s name and city, but not full address. He then asked the intermediary to send the letter on to a friend who they thought might be able to get it closer to its final target. The goal was to discover the number of social links that were needed to connect two people selected at random within the United States.

Although most of Milgram’s letters never reached their destination, those that did took on average only six links to be delivered. Hence the “six degrees” that supposedly separate us all.

With the arrival of the internet, these sorts of experiments have become much easier to conduct. You can play a similar game yourself at the Oracle of Bacon, a site which searches imdb to find the number of co-starring relationships that separate any actor from Kevin Bacon. Rhys Darby has a Bacon number of two: he co-starred in “Yes Man” with Albert Miranda, who in turn co-starred with Bacon in “Frost/Nixon”. The average Bacon number in the database is just under three, and the average Darby number is roughly three and a half.

Both the Oracle of Bacon and Stanley Milgram’s experiment illustrate that individuals within large social networks are connected by relatively short paths. Not all networks are “small”. Think of your family tree:  to follow your tree to your cousin, you’ll need four links (I hope) i.e. you to your parent to your grandparents to your aunt (or uncle) to your cousin. That’s already more than the average Bacon number, and in a network that only contains your extended family. Of course, you probably have direct social links with your cousin – this illustrates that social networks are different in structure to family trees.

Networks in which two individuals selected at random can be connected by a relatively small number of links are called small world networks. There are several popular books that discuss the science and mathematics of small world networks – I can recommend Six Degrees by Australian physicist turned sociologist Duncan Watts.

Scientists have identified other small world networks, including the internet and the world wide web. As I discussed in an earlier post, my research group has looked at networks of inventors. Networks of inventors turn out to be almost, but not quite, small world networks. Let’s call them medium world networks for now. They also share some features in common with the hyperlink structure of the web. But most interesting is that some of their properties do depend on network size, i.e. the properties of your collaborative network depend on the number of people in the network. This has implications for a small country like New Zealand – I’ll discuss this further in a later post.

So … are New Zealanders separated socially by only two degrees? Actually, a quick scribble on the back of the envelope suggests to me that it’s about four and a half: “4.5degrees” is not quite as catchy for a phone company, although it does conjure up an image of somewhere slightly warmer (possibly planet Earth by 2050). Still, I usually tell my students not to worry too much about factors of two, so I guess I can live with the “2degrees” ads provided they carry on being funny. Perhaps someone would like to design a Kiwi Milgram test to measure this …  how many links separate you from Rhys Darby?

Networks of inventors Shaun Hendy Sep 28

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Several people in my research group have been studying an OECD patent database recently. We were particularly interested in whether we could find evidence for collaborative networks of inventors. Almost all researchers collaborate with other researchers to some extent, but it was not clear to us that these collaborations would show up in the patent literature. While each patent application must name the inventors that have directly contributed to the invention, indirect contributions from unnamed researchers would be invisible to the database.

So when we started it wasn’t clear that we would find collaborative networks of inventors at all. However, we have now found many large communities of inventors who are connected by patents. In fact it turns out that these networks are similar in some ways to the small-world networks that exist in social groupings or between web pages, with hubs that form around highly inventive people. I’ll talk in more detail about structure of these co-inventor networks in another post.

The largest network we have found is in California, stretching from San Francisco to San Diego and connecting approximately 24,000 inventors. As far as we can tell, there doesn’t seem to be anything else like it in the world – the next largest networks are less than 10,000 inventors in size, and are dominated by large firms like Philips or Sun Microsystems. However, the inventors in this large Californian network come from a diverse range of organisations, seemingly a mix of small health-care and pharmaceutical companies. There is definitely something in the water in California.

Helsinki The other network that has fascinated me is much smaller. It consists of about 1300 inventors in the Helsinki region in Finland, whose patents are owned by Nokia (appropriately Nokia’s current slogan is “Connecting People”). A representation of the network is shown on the right – the red dots (“nodes”) show individual inventors, with the lines (“edges”) between dots indicating that the two inventors share a patent. This network formed as Nokia transformed itself from a relatively small consumer electronics company to a globally dominant mobile phone manufacturer over the period 1993-2008 .

Finland output growth The largest network we can find in New Zealand consists of less than 40 people. So I find it remarkable that a co-inventor network of 1300 people exists in a country with a population similar to New Zealand. Finland’s patent and publication statistics from the early 1990s do not suggest that they were any stronger than New Zealand in information and communication technology. Yet by the end of the decade they were vigorously patenting and writing papers in ICT, and had increased their electronics exports tenfold to more than NZ$20 billion per annum (shown on the left). No matter how you look at it, this was a remarkable economic transformation.

Of course, Finland was lucky that Nokia emerged with the right product at the right time, but to exploit this luck to become the dominant player in the world cell-phone market, they apparently drew on this very large pool of inventors.

Where did they get that inventive talent from? I gave a talk on this in June at MoRST where someone suggested that there may have been an influx of Russian scientists and engineers after the collapse of the Soviet Union. However, the inventors names in the database are distinctly Finnish – it appears that the Finns trained Nokia’s inventors in their universities. While in the 1980’s, less than 50 engineering PhDs were graduating from Finland’s university each year (close to New Zealand’s current total), early in the 1990s this started to grow, and by the end of the decade the figure had tripled. In a later post, I’ll look at this in more detail.