On 15 July 2016 at 08:44, James Heilman jmh649@gmail.com wrote:

Thanks for the in depth discussion. So if the terms people are using that result in "zero search results" are typically gibberish why do we care if 30% of our searches result in "zero search results"? A big deal was made about this a while ago.

Good question! I originally used to say that it was my aspiration that users should never get zero results when searching Wikipedia. As a result of Trey's analysis, I don't say that any more. ;-) There are many legitimate cases where users should get zero results. However, there are still tons of examples of where giving users zero results is incorrect; "jurrasic world" was a prominent example of that.

It's still not quite right to say that *all* the terms that people use to get zero results are gibberish. There is an extremely long tail https://en.wikipedia.org/wiki/Long_tail of zero results queries that aren't gibberish, it's just that the top 100 are dominated by gibberish. This would mean we'd have to release many, many more than the top 100, which significantly increases the risk of releasing personal information.

If one was just to look at those search terms that more than 100 IPs searched for would that not remove the concerns about anonymity? One could also limit the length of the searches displaced to 50 characters. And just provide the first 100 with an initial human review to make sure we are not miss anything.

The problem with this is that there are still no guarantees. What if you saw the search query "DF198671E"? You might not think anything of it, but I would recognise it as an example of a national insurance number https://en.wikipedia.org/wiki/National_Insurance_number, the British equivalent of a social security number [1]. There's always going to be the potential that we accidentally release something sensitive when we release arbitrary user input, even if it's manually examined by humans.

So, in summary:

- The top 100 zero results queries are dominated by gibberish. - There's a long tail of zero results queries, meaning we'd have to reduce many more than the top 100. - Manually examining the top zero results queries is not a foolproof way of eliminating personal data since it's arbitrary user input.

I'm happy to answer any questions. :-)

Thanks, Dan

[1]: Don't panic, this example national insurance number is actually invalid. ;-)