I wouldn't bet on it. Amazon knows exactly what I just bought and still shows me 100 different variations on it "recommended" for me.

Right?! God dammit Amazon, I just bought a crock pot! You know that! Why do you still serve me ads about crock pots!? The whole point of the surveillance state is to make use of all that info you have on me - frankly, it's insulting. I demand a better big brother!

It drives me nuts when I log in to Amazon and it keeps showing me all these parts for building a new PC.

Damnit Amazon I just built one! How many processors do you think a single gaming PC can fit?!

I've often wondered why they do this. I see more variations of items I just purchased rather than accompanying/related items.

it works for a lot of cases, e.g. buy a book and get other books recommended, not so well for rarer purchases like laptops or phones.

I still get recommendations for the same book I just bought, but in different editions/formats. Seems like it could be improved some more.

But be careful of the 'Perfect Partner / frequently bought with...' recommendations, which Amazon themselves disavow as being in any way compatible:

If two items listed as Perfect Partner / Frequently Bought Together are not compatible, Amazon.co.uk are unable to accept the return of either item for this reason.

That's because it is just doing item-based collaborative filtering, right? It works beautifully other times. I bought chopsticks once and it showed me not more chopsticks, but other accessories for sushi, etc.

I wouldn't be so sure, I am positive Amazon still bombards me with Kindle Ads despite owning a couple already :)

Sounds like the ads are super effective then.

It has always struck me as odd that Amazon shows me ads for things I had searched for and didn't buy as though I didn't already know about those products. Seems they should perhaps show me what other people bought that searched for similar or the same products as myself.

There was some talk of this on HN a while back, where the marketing theory presented was that there is a noticeable increase in sales if the customer walks away from a sale but is then later reminded of the product they almost bought.

From my experience with retargeting it drives amazing lift in conversions. A lot of platforms allow you to do this dynamic ad placing where you show the recently added item in a cart, but not purchased.

Also, let's not forget that Amazon is obsessed with testing, I am sure they have troves of it to back up everything they are doing.

I walk away from purchases plenty of times not because I don't want to buy the thing I searched for, but because something more pressing comes up.

Reminding me about the thing I was about to buy is very likely to get me to buy it in those cases.