The question is whether this additional effort is strictly necessary or whether it’s just nice to have.

Why do complicated things when something simple already works pretty well? Your thinking that just because something is possible it will be done is not very close to the practical reality in the trenches. Because something is possible it might be done if resources are there. If not, best effort, done.

All of this analysis is expensive, so don’t expect it all to be done.

How do you detect the absence of a visit if all you have is a hidden pixel on a page?

Okay, let me rephrase. If you have tracking pixel logs that show his having searched for faucets for a while, and then that stops, what does it sound like?

Theory A: He wasn't shopping for faucets at all, he's just a bot following links and who had recently visited a faucet portal page.

Theory B: He searched, found a faucet he liked and bought it.

Theory C: He searched, then installed Ghostery, and is still in the market for a faucet.

All are possible, but one of them sounds a lot more likely than the other two to my ears.

Let's assume Theory B is correct, and searching for a faucet and then stopping can be treated as having bought a faucet. That tells the advertiser that the user buys faucets, and that's exactly the right person to advertise to. I'd bet that in a large number of cases someone who buys a faucet is likely to buy another faucet in the near future - faucets are something that you buy when you're doing up a house, or you've moved house, etc.

Advertising to someone who you have reason to believe is going to buy your product is much more effective than advertising to an unknown person.

>>Advertising to someone who you have reason to believe is going to buy your product is much more effective than advertising to an unknown person.

Totally depends on the product and the person you are marketing to. Marketing hammers to carpenters makes sense: they use many different types, and presumably go through them quickly. Marketing faucets to regular folks is a dumb thing to do. A faucet is something you buy once in a blue moon.