Anti-Neocons

Starting this fall, you’ll have a new reason to trust the information you find on Wikipedia: An optional feature called “WikiTrust” will color code every word of the encyclopedia based on the reliability of its author and the length of time it has persisted on the page.

Now, researchers from the Wiki Lab at the University of California, Santa Cruz have created a system to help users know when to trust Wikipedia—and when to reach for that dusty Encyclopedia Britannica on the shelf. Called WikiTrust, the program assigns a color code to newly edited text using an algorithm that calculates author reputation from the lifespan of their past contributions. It’s based on a simple concept: The longer information persists on the page, the more accurate it’s likely to be.

Since Wikipedia already keeps track of every revision, de Alfaro realized he could use that data to create a reputation system independent of human input. “Machines should work for humans and not the other way around,” he said. “So if you can get information without bothering people, via clever algorithms, this is much better.”

The Wiki Lab built its trust tool around the principle that Wikipedia pages tend to improve over time, or at least to move toward consensus. You can measure an author’s trustworthiness by looking at how long his or her edits persist over time, said UCSC graduate student Bo Adler, who developed WikiTrust with de Alfaro and graduate student Ian Pye. “When you add something to Wikipedia and it lasts a long time, you did a good job,” Adler said. “If it gets erased right away, you did a bad job.”

Based on an person’s past contributions, WikiTrust computes a reputation score between zero and nine. When someone makes an edit, the background behind the new text gets shaded orange depending on their reputation: the brighter the orange, the less “trust” the text has. Then when another author edits the page, they essentially vote on the new text. If they like the edit, they’ll keep it, and if not, they’ll revert it. Text that persists will become less orange over time, as more editors give their votes of approval.

“We try to predict when things are going to be deleted,” Adler said. “We want words that are going to be deleted to have a low trust, and words that are not going to be deleted to have a high trust.”

But some critics think there may be hurdles to running the trust tool over the entire site. “This isn’t a trivial web architecture design and implementation issue,” said computer scientist Ed Chi of the Palo Alto Research Group, who studies Wikipedia and social cognition. Since WikiTrust assigns a reputation score to every word in every article, running the program in real time will demand significant processing power and several terabytes of extra disk space.

But Wiki Lab researchers say they’re already working on making the program more efficient. Using the first version of WikiTrust, it took a regular computer 20 days to process five years of Wikipedia revision data. The latest edition cuts that time to four days, and it can calculate trust ratings for 30 to 40 revisions per second. “That’s on a single machine,” Adler said. “So it’s very practical for us to keep up with Wikipedia.”

It’s based on a simple

concept: The longer information persists on the page, the more accurate it’s likely to be.