98.9% not porn

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Like everyone else, SiliconValley.com is covering the recent DOJ study on the prevalence of pornography on the Internet. Unlike everyone els,e they provide links to the original study. The key findings seem to be:
  • Approximately 1.1% of the sites in Google and MSN's indexes are sexually explicit.
  • A little under half of the sexually explicit websites are domestic (US).
  • Almost 40% of the "most popular" queries retrieved a sexually explicit website.
  • Approximately 6% of queries return a sexually explicit website.
  • There's a tradeoff between filter sensitivity and specificity, but basically none of the tested filters had reasonable type I and type II error rates.

It's not entirely clear what the implications of this data are for policy. We have to be concerned with two ways in which children would access pornography:

  • Intentionally looking for it.
  • Accidentally running into it in the course of ordinary searches.

It should be pretty clear at this point that if someone is intentionally looking for pornography, they'll be able to find it, but that's certainly not news to anyone who's paying attention. Whether the fraction of pornographic web sites is 1.1% or .11%, all it takes is 30 seconds of Google searching (or checking out Fark) to convince yourself that there's plenty of it and it's easy to find. It's also clear that filters don't do a very good job of blocking pornography, but that's not really news either.

That leaves us with children accidentally running into pornography. I don't see that this study tells us much about that at all. I'm quite prepared to believe that the the most popular searches turn up pornography, but that doesn't tell us anything about whether those searches were explicitly for pornography--of which I imagine there's quite a bit--or searches that just accidentally turned up pornography. To answer this question you'd need to examine the search terms that people were using and try to make some judgement about their intentions. Without doing that, it's hard to estimate the likelihood that someone who wasn't looking for porn would run into it anyway, which is what's relevant here.


"We have to be concerned with two ways..."

This assumes that dealing with this issue at all is something worth doing (or, depending on your meaning, cause for concern even). I would dispute that premise.

Fair enough. I meant concerned for the purposes of analysis. I agree that this issue is a big waste of time and money.

I wouldn't be surprised if 40 per cent of the most popular searches were for filth.

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