Thanks Carl!

In the year 2000 internet access itself had 7% global penetration, and 31% penetration in the developed world; your estimate seems to assume that people with no internet access were getting substantial benefits out of Google

I was trying to wash out this issue by weighting for income, but maybe the implicit adjustment wasn't large enough. Do you have an idea of what the fraction of world GDP corresponds to that 7% of the population?

Search use was less intensive at that time, e.g. because of annoying dial-up connections instead of broadband, the absence of mobile internet, lack of content to search for... see these two pages for data on search traffic, which is up close to two orders of magnitude since 2000

Very good point.

Services like AltaVista were definitely worse, but could still find pages and were improving, so the value contributed is only the difference between the engines

I had this in mind.

5% of income is way too high to be credible for willingness-to-pay: 20% of American households in 2011 weren't willing to pay for internet access, which includes the marginal search quality of Google among many other features, for a lower cost

Yes, I suspected that my figure was way too large, but wanted to be liberal. Do you have an idea for a suitable anchor for a plausible upper bound? I could replace "5%" by "1%" but that feels too ad hoc....

Even $1/week might be too much for much of the world's population, and even a nontrivial chunk of the developed world: people who won't pay $10-20/month plus computer costs for internet access itself plausibly wouldn't pay $4/month for marginal Google search quality

Here too, I was trying to wash this out by weighting for income, and considering somebody making $45,000/yr.

On the plus side better search encouraged the development of more websites and internet businesses with various good effects

Do you believe that the effects are out of proportion with what people would have been willing to pay to use Google (relative to counterfactual uses of money)?