Its funny you should use that example. I recently bought a rice cooker, and then bought another a few weeks later.

I've done similar things a lot, in this case it was because the first cooker had too large a minimum cooking amount. I'm currently looking at buying my mother google WiFi - which I bought a few weeks ago. And a few months back I rebought a tool I had just purchased because I lost it.

I currently work for a (responsible) own site adtech (personalization) company. Its surprising what behaviours our clients find profitable for their business.

There's a whole lot about advertising I don't know, but the question that sticks in my mind is, did you need that ad to know which rice cooker to buy the second time? Did it change your decision? Did you see an ad for a different rice cooker and act on that?

It seems like an effective ad would be this: Say you bought a rice cooker on Amazon for $75. Now Walmart shows you an ad for the same rice cooker for $60. That would certainly stick in my head- not for the rice cooker but for the price difference that Walmart can provide.

These are amazon internal adds, they don’t care about the specific rice cooker they show as much as the rice cooker category. Thus simply getting you to think about them while you’re on the website is enough they don’t need to predict your specific purchase.

Yes. Without the ads I wouldn't have bought the second cooker - it was a pain point for my partner not for me, so she complained once then a week or two later I saw the ad and purchased another.

With the Google wifi I had forgotten, and it caused me tk reconsider and write it on my whiteboard.

The tool I wpuld purchase anyway.

You said you work for adtech, I'd just like to comment that I personally like targetted ads. Areas of my life have improved from targetted ads, I'm shown things I didn't even know I want until I've seen them, etc. I look at it as a positive.

Its an interesting one. I've made some pretty active choices about jobs for ethical reasons but ended up in a slight geographical bind in my last search. I found my current company through a friend (who works in another department) and was very skeptical. After not finding anything bad I decided to go with it for a few months, but had a resignation letter ready in my car. I'm now over a year in and despite the normal problems businesses have there is not a moral one here - and I've had pretty great insight into the decision making.

It's not as simple as that. There are multiple ways to figure out which ad to show to a user, but I think the most efficient way (development and compute) is to put a user in segments (e.g. lives in area X, searched for Y, age Z, ...) and then do the bidding magic. There are tight tolerances for bidding--you want it to happen within a fraction of a second so the ad quickly loads for the user. Feeding purchase data is likely something that requires a bit of work, and I imagine the ad team at Amazon doesn't see enough value to prioritize it (especially since they make money either way--the advertisers pay for the ad with a higher CPC).

One thing to keep in mind is that the purchase data is per-user, so it's different from the segment approach I was mentioning above. It would require a whole new schema* that is queried whenever bids are processed for an ad event.

* Sorry for using the word schema here. It was used a lot on a team I was on in a similar context, and it bothered me at first but I got used to it. What I mean by schema is a "blob" with purchase data that is periodically processed by the bidding subsystem to add bid exclusions per user.

What is the ratio between people who viewed a rice cooker (the group I'm assuming they target with ads) vs. those who actually bought a rice cooker?

Is it possible the ratio is so large to where while it obviously could be optimized to exclude people who have since purchased said item - the optimization is only a rounding error, and may not turn out to be worth it?

Well, I buy things from Amazon very frequently, and I have a high conversion rate between searched-for-category and bought something to satisfy the search, so Amazon ads are for things I've already taken care of >90% of the time. I'm guessing they're leaving a lot of money on the table from me because of it. But maybe I'm unusual in my shopping patterns.