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Comment by Zak | Hacker News Reader

Amazon has been repeatedly showing me office chair casters as a suggestion after I bought a set on Amazon.

Despite having much better information on things I actually spend money on than the average ad network (all my devices have adblockers), Amazon isn't clever enough to figure out that I'm probably done with that product category for years.

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To explain how this happens will take several pages of notes on the complexities of ad serving that are the exact opposite of "not clever enough".

A summary is that your adblocking may have an impact on syncing stats, your purchases are not unique enough to matter for that category, serving some ad is better than serving no ad, and it maybe better to show you that impression however worthless than to bother with something else considering the auction dynamics at that point in time.

Do you think that's true when it comes to Amazon's recommendations, which I'm assuming are largely based on activity on Amazon itself? My adblockers don't keep Amazon from tracking things I do on their site while logged in, nor from showing me product recommendations.

Actually before I was ad blocking, two large local electronics stores did the same stupidity. I bought some expensive electronic toy, then was followed for a week by google ads for the exact same electronic toy. Which i had just bought. And was expensive enough to not buy another. And the ads were for the EXACT SAME STORE i had just bought it from.

I repeat, that was before I began blocking ads. For a while I was on the 'let the web sites make some money' side. Then the web sites became unreadable with ads on so it's uBlock Origin now.

That's what I described about the ecommerce system being different than the ad network. Products usually have their own pages where you can easily be added to a 'interested' segment.

It's very hard to remove you from that segment on a consolidated check out page that would need some backend mapping with the products you bought and the removal pixels for each product and ad network, along with lots of other issues. It's just not that simple as you may think to keep things in sync.

So they're okay with me considering them stupid? :)

As the customer, I don't care how hard or easy it is. I can imagine how it would be implemented, but 99% of the world population can't.

Note that they never gave me ads for stuff i only looked at, only for stuff that went through my shopping cart. If it's already there, I guess it makes figuring out if i bought it or not easier?

The explanation I've seen is that yes, most people who buy certain products (a microwave oven, say) are probably done for a long time and less likely than the average person to buy one, but overall the group of people who just bought a microwave oven are still much more likely than the average person to buy another one. So yeah there are a bunch of people for whom the ads seem extremely stupid because of course you don't need another one, but enough who think "you know, I could use one in (the camper/the basement/the rental/the garage-office), actually, but it'll need to be a smaller one" that it's worth advertising other options to the whole group. (for the record, I hate all ads and wish they'd go away)

I've read loads of suggested explanations for why this is a thing over the years, and none of them have ever felt satisfactory to me.

However, none of the people doing this really care why this is a thing, they care that, for some reason, this is a thing. It's vastly more profitable than nearly every other type of advertising, and since nobody _really_ knows how that works either, they just follow their tried and tested patterns that work.

Obvious _you_ wouldn't be this dumb. But it turns out that, on average, you are exactly this dumb ...

I suppose it might be true that the sort of person who buys 50 sets of office chair casters first buys one set to try out, and if they're happy with that, comes back for more in a week. The chance that I might be that person is relatively high reward (a ~$1000 sale), and Amazon doesn't have a better idea of what I'm going to buy.

The simple answer is that there's a far greater number of people who saw the product but didn't buy then those who did. Conversions are a tiny percentage that scales with price, so showing ads to everyone who saw it raises that conversion rate.

It doesn't really affect the people who already bought it since the conversion is complete, and the wasted impressions are trivial compared to the cost of implementing more complex tech to keep things in sync.

Perhaps there's a secondary effect of negative reputation from seeing ads for stuff you bought but the data doesn't bear it out.

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