Visualising edit history of a Wikipedia page

Quick post (really should be doing something else). Reading Jeff Atwood's post Mixing Oil and Water: Authorship in a Wiki World lead me to IBM's wonderful history flow tool to visualise the edit history of a Wikipedia page.

Imagine a scenario where three people will make contributions to a Wiki page at different points in time. Each person edits the page and then saves their changes to what becomes the latest version of that page.

History Flow connects text that has been kept the same between consecutive versions. Pieces of text that do not have correspondence in the next (or previous) version are not connected and the user sees a resulting "gap" in the visualization; this happens for deletions and insertions. (animated GIF from Jeff Atwood's post).

There's a nice paper describing history flow (doi:10.1145/985692.985765, free PDF here). Inspired by this I decided to try and implement history flow in PHP and SVG. Here's a preliminary result:

This is the edit history for the Afrotheria page. Click on the image above (or here to see the SVG image -- you need a decent web browser for this, IE uses will need a SVG plugin).

The SVG image is clickable. The columns represent revisions, click on those to go to that revision. The columns are evenly spaced (i.e., the gaps don't correspond to time). The bands between revisions trace individual blocks of text (in this case lines in the Wikipedia page source). If you click on a band you get taken to that Wikipedia user's page.

This is all done in a rush, but it gives an idea of what can be done. The history flow carries all sorts of information about how an article has developed over time, major changes (such as the introduction of Taxoboxes), and makes the content of a page traceable, in the sense that you can see who contributed what to a page.

Google and Wikipedia revisited

Given that one response to my post on Fungi in Wikipedia was to say that fungi are also charismatic, so maybe I should try [insert unsexy taxon name here]. So, I've now looked at all the species I extracted from Wikipedia (nearly 72,000), ran the Google searches, and here are the results:

Site	How many times is it the top hit?
en.wikipedia.org	42515
www.birdlife.org	2125
commons.wikimedia.org	1522
plants.usda.gov	1496
species.wikimedia.org	1487
animaldiversity.ummz.umich.edu	1419
amphibiaweb.org	851
www.calflora.org	770
www.fishbase.org	727
ibc.lynxeds.com	699
davesgarden.com	659
www.arkive.org	510
ukmoths.org.uk	414
zipcodezoo.com	368
www.itis.gov	304
calphotos.berkeley.edu	294
www.floridata.com	234
www.planetcatfish.com	234
www.eol.org	226
www.arthurgrosset.com	213

The table lists the top twenty sites, based on the number of times each site occupies the number one place in the Google search results. Surprise, surprise, Wikipedia wins hands down.

What is interesting is that the other top-ranking sites tend to be taxon-specific, such as FishBase, Amphibia Web, and USDA Plants. To me this suggests that the argument that Wikipedia's dominance of the search results is because it focusses on charismatic taxa doesn't hold. In fact, the truly charismatic taxa are likely to have their own, richly informative webs sites that will often beat Wikipedia in the search rankings. If your taxon is not charismatic, then it's a different story. This suggests one of two strategies for making taxon web sites that people will find. Either go for the niche market, and make a rich site for a set of taxa that you (and ideally some others) like, or add content to Wikipedia. Sites that span across all taxa will always come up against Wikipedia's dominance in the search rankings. So, it's a choice of being a specialist, or trying to compete with an über-generalist.

Fungi in Wikipedia

One response to the analysis I did of the Google rank of mammal pages in Wikipedia is to suggest that Wikipedia does well for mammals because these are charismatic. It's been suggested that for other groups of taxa Wikipedia might not be so prominent in the search results.

As a quick test I extracted the 1552 fungal species I could find in Wikipedia and repeated the analysis. If anything, the results are more dramatic:

Once again, Wikipedia dominates the search rankings. Over 75% of the pages are the top hit in Google. More specialist fungal sites, such as CAB Abstracts Plus and the American Phytopathological Society's online database do pretty well. EOL and the nomenclatural database Index Fungorum barely make an appearance.

If fungi are less "charismatic" than mammals, the implication is that the less charismatic the taxon, the better Wikipedia does (perhaps there is less competition from other sites). Of course, Wikipedia is severely underpopulated with fungal pages, so one could argue that for fungi not in Wikipedia, sites like EOL may do better (relative to other sites), but that would need to be tested. I suspect that sites that provide more broadly useful information (such as APSnet) will continue to dominate the search rankings, followed by scientific articles (for the fungi in Wikipedia the publishers Springer, Wiley, and Elsevier all appear in the top of sites that appear in the Google rankings).

Wikipedia mammals and the power law

Playing a bit more with the Wikipedia mammal data, there are some interesting patterns to note. The first is that rank the mammal pages by size (here defined as the number of characters in the source for the page) and plot size against rank then we get a graph that looks very much like a power law:

There are a few large pages on mammals (these are on the left), and lots of small pages (the long tail on the right). If we do a log-log plot we get this:

The straight line is characteristic of a power law. The dip at the far right reflects the fact that Wikipedia pages have a minimum size (for example, they must include a Taxobox). Now, this is a bit crude (I should probably look at "Power-law distributions in empirical data" arXiv:0706.1062v2 before getting too carried away), but power laws are characteristic of the link structure of the web (a few big sites with huge numbers of links, huge numbers of sites with few links), and indeed of at least parts of Wikipedia, such as the Gene Wiki project (see doi:10.1371/journal.pbio.0060175).

In this context, the diagrams are showing that even if mammals are "charismatic megafauna", most of them aren't that charismatic. Wikipedia mammal pages are mostly small. This raises the question of whether the high frequency in which Wikipedia mammal pages appeared in the top of Google searches might be attributed to those large pages on (presumably) charismatic mammals. If this were the case, then we'd expect that small pages wouldn't rank highly in Google searches. So, I plotted page size against Google search rank for the Wikipedia mammal pages:

This is a box plot, where the grey boxes represent 50% of the distribution of page size (the horizontal black line is the median), and extreme values are shown as circles. Note that "0" is the highest rank (i.e., the first hit in Google), and 9 is the lowest.

While, not surprisingly, most large Wikipedia pages do well in Google searches, and rarely are large pages low down the rankings, my sense is that small pages can have any rank, from top (0) to bottom (9). If page size (i.e., which is a crude measure of the effort put into editing a Wikipedia page) is a measure of "charisma" (contributors are more likely to edit pages on animals that lots of people know about), then charisma isn't a great predictor of where you come in Google's search results. It's not about size, it's about being in Wikipedia.

Google, Wikipedia, and EOL

One assumption I've been making so far is that when people search for information on an organism using its scientific name, Wikipedia will dominate the search results (see my earlier post for an example of this assumption). I've decided to quantify this by doing a little experiment. I grabbed the Mammal Species of the World taxonomy and extracted the 5416 species names. I then used Google's AJAX search API to look up each name in Google. For each search I took the top 10 hits and recorded for each hit the site URL and the rank in the search results (i.e., 1-10). Below is a table of how many mammal species had a hit in the top 10 Google results (showing just the top 20 most frequent sites).

Site	Hits
en.wikipedia.org	5266
species.wikimedia.org	2934
animaldiversity.ummz.umich.edu	2890
commons.wikimedia.org	1515
www.itis.gov	1418
ctd.mdibl.org	1288
www.bioone.org	1101
www.uniprot.org	1086
encyclopedia.farlex.com	1007
www.thewebsiteofeverything.com	955
www.answers.com	864
vertebrates.si.edu	854
www.interaktv.com	842
www.arkive.org	775
linkinghub.elsevier.com	727
www.springerlink.com	656
www.eol.org	618
www.reference.com	576
doi.wiley.com	572
noctilio.com	566

Wikipedia is the clear winner, with 5266 (97%) of mammals having a Wikipedia page in the top ten Google results. Next comes Wikispecies, then Animal Diversity Web, Wikimedia Commons, ITIS, the Comparative Toxicogenomics Database, BioOne, UniProt (derived from the NCBI taxonomy), and so on. Note that the Encyclopedia of Life comes in 17th.

Things get more interesting if we look at the ranking of search results. The graph below plots the cumulative rank of search results for some of the web sites listed above.

Wikipedia dominates things. For 48% of all mammal species Wikipedia is the first result returned by Google. Just under three quarters of all mammal species are either the first or second top hit in Google. The next best sites are Animal Diversity Web and Wikispecies, which get a small share of first place for some species (19% and 7% respectively). Note that EOL pages manage to make it into the top 10 for only 11% of all mammal species.

What does this all mean? Well, it seems clear that if people are using Google to find information about an organism, then Wikipedia is more likely than anything else to be the first result they see. It is also interesting that for all the energy (and funds) being expended on biodiversity databases (doi:10.1126/science.324_1632), ITIS is the only classical biodiversity database that routinely gets found in these searches (albeit in only a quarter of the searches).

I know I tend to go on a bit about EOL, but if I was running (or funding) EOL, I'd be worried. EOL barely figures in these search results, and is being taken to the cleaners by a volunteer effort (Wikipedia). Furthermore, it seems difficult to envisage what EOL can do to improve things. Sure it can link to (and make use of) content in sites such as Animal Diversity Web, ITIS (and maybe even, gasp, Wikipedia), but that just adds "link love" to those sites. Ironically, perhaps the single thing that would improve EOL's ranking would be if Wikipedia spread some of its link love over EOL, by linking all it's taxon pages to the corresponding EOL page.

But there are bigger issues at stake. Site popularity on the web tends to follow a power law, where a very few web sites grab the vast majority of eye balls. In a old blog post Clay Shirky wrote:

Now, thanks to a series of breakthroughs in network theory by researchers ... we know that power law distributions tend to arise in social systems where many people express their preferences among many options. We also know that as the number of options rise, the curve becomes more extreme. This is a counter-intuitive finding - most of us would expect a rising number of choices to flatten the curve, but in fact, increasing the size of the system increases the gap between the #1 spot and the median spot.

So, creating new and improved biodiversity web sites is likely to have the effect of only increasing the gap between Wikipedia and the rest.

Lastly, as I've mentioned before regarding Wikipedia and citations of taxonomic work, the graph above suggests to me that for anybody wanting to make basic biodiversity information available on the web, and attract readers to basic taxonomic literature, there really is only one game in town.