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I don’t understand why this is such an obviously bad strategy - lots of people buy an item, cancel or return it, and then buy a similar item.

cgriswald 6y ago
Let’s say you buy a washing machine on Amazon. You’re not likely to need more than one. Amazon knows whether you canceled or returned your order. So the only way it makes any sense is if Amazon is advertising on the chance that you’re going to cancel or return it in the future. Amazon certainly has those numbers. But do you think the chance you’re going to cancel or return it is so high Amazon should advertise the same product to you instead of something else you might buy?
- grandmczeb 6y ago
  > But do you think the chance you’re going to cancel or return it is so high Amazon should advertise the same product to you instead of something else you might buy? It’s not either or - Amazon showed me grill accessories along with other models when I bought a grill. Regardless, I don’t really have a hard time believing that even a small chance of buying and canceling could make the expected value of showing that item higher than other items, even if that’s counter intuitive to you. I have a harder time believing that what’s shown is not well optimized and “obviously” wrong.
  - danaris 6y ago
    Any individual spot Amazon is advertising you something they could easily know you will not buy is a spot they could have instead used for an ad for something they do not have this knowledge about. So yes, it is either/or.
    - grandmczeb 6y ago
      The point is that if you have multiple ad slots you can cover a wider range of buyers. For example, the chances that someone would click on a 5th grill accessory ad is probably pretty low if they didn’t click on any of the previous 4. But if they’re thinking of returning the grill they already purchased, they might be interested in a different model. Averaged over all buyers, the best strategy might well be to show a mix of accessories and other models. Or, depending on the numbers, all grills or all accessories could also make sense. My broader point is that it’s perfectly possible the best strategy doesn’t line up with people’s intuition, which is why we use ML for recommendations in the first place.
      - Skunkleton 6y ago
        Or even better: show a grill accessory, but also show some other stuff perhaps unrelated to my new found love of buying and returning grills?
      - cgriswald 6y ago
        I'm trying to imagine a scenario where someone returns a single-purchase item and then purchases the same exact item as the result of seeing an ad for it. They're already aware of the item and if they want another one after return they're probably just going to exchange it because something is wrong with it. It's not even a sale and I'm skeptical that seeing the ad has a strong influence on whether a customer asks for a refund or a replacement. ML is not some holy grail that always produces optimum algorithms. It depends heavily on inputs and on the assumptions, both explicit and implicit in the training data. My guess is Amazon does not have a "single-purchase item" model and it's not something the AI was trained to identify and so they aren't specifically excluded from groups of "similar-or-same" items. I think it is far more likely that Amazon is optimizing the cost of development against the marginal benefit of not showing ads for single-purchase items than that this is somehow driving more sales.
        grandmczeb 6y ago
        I’ve personally done the following: 1. Buy a large ticket item (e.g. furniture). 2. See an ad on Amazon for a different/nicer/better/faster shipped version. 3. Buy it. 4. Cancel the old order. Is that a common pattern? No idea. But it’s not crazy to me that it happens often enough that it’s worth it to Amazon to show similar items to people who already bought them.
      - danaris 6y ago
        I mean, sure, I don't have any scientific studies to back this up. But I really don't feel like this is a case where "intuition might be completely wrong" applies—buying a $400 grill, and then just going back and buying 3 more $3-500 grills, just isn't something that people do on a regular basis. Same for vacuum cleaners, refrigerators, etc. And yet Amazon does regularly advertise these things to us after such large purchases. The only logical conclusion is that it's cheaper for them (in the short term, at least) not to update their ad/recommendation algorithm to take into account the nature of large one-time purchases.
frogpelt 6y ago
Would you say the majority of people shop like that? It makes sense to me that if I buy post hole diggers you should show me ads for work gloves or mailboxes or fences. Not more post hole diggers. Weird example, I know.
- grandmczeb 6y ago
  I mean, I’ve definitely done it and I’ve seen other people do it. I have no idea how typical it is.
- jacobr1 6y ago
  That would probably be a better strategy. But if you are looking at a naive, single variable, a prior purchase is the greatest single predictor of future purchases. If you know nothing else about a person, the fact you purchased one post-hole digger makes it more likely you'll purchase another, as opposed to some random other internet denizen for which we know nothing. Having worked in email marketing analysis before, this effect was surprisingly robust across categories. It implies you are the kind of person that could use such a product - most people aren't.
marblessubtext 6y ago
I bought a quality vacuum from Amazon and then continued to be aggressively advertised vacuums for months (on Amazon still) while shopping for things that honestly I could have used some advertising for to let me know what even existed in the space. Seems like not a great strategy for any involved party. They never advertised bags for said vacuum...

cgriswald 6y ago

Let’s say you buy a washing machine on Amazon. You’re not likely to need more than one. Amazon knows whether you canceled or returned your order. So the only way it makes any sense is if Amazon is advertising on the chance that you’re going to cancel or return it in the future. Amazon certainly has those numbers. But do you think the chance you’re going to cancel or return it is so high Amazon should advertise the same product to you instead of something else you might buy?

grandmczeb 6y ago
> But do you think the chance you’re going to cancel or return it is so high Amazon should advertise the same product to you instead of something else you might buy? It’s not either or - Amazon showed me grill accessories along with other models when I bought a grill. Regardless, I don’t really have a hard time believing that even a small chance of buying and canceling could make the expected value of showing that item higher than other items, even if that’s counter intuitive to you. I have a harder time believing that what’s shown is not well optimized and “obviously” wrong.
- danaris 6y ago
  Any individual spot Amazon is advertising you something they could easily know you will not buy is a spot they could have instead used for an ad for something they do not have this knowledge about. So yes, it is either/or.
  - grandmczeb 6y ago
    The point is that if you have multiple ad slots you can cover a wider range of buyers. For example, the chances that someone would click on a 5th grill accessory ad is probably pretty low if they didn’t click on any of the previous 4. But if they’re thinking of returning the grill they already purchased, they might be interested in a different model. Averaged over all buyers, the best strategy might well be to show a mix of accessories and other models. Or, depending on the numbers, all grills or all accessories could also make sense. My broader point is that it’s perfectly possible the best strategy doesn’t line up with people’s intuition, which is why we use ML for recommendations in the first place.
    - Skunkleton 6y ago
      Or even better: show a grill accessory, but also show some other stuff perhaps unrelated to my new found love of buying and returning grills?
    - cgriswald 6y ago
      I'm trying to imagine a scenario where someone returns a single-purchase item and then purchases the same exact item as the result of seeing an ad for it. They're already aware of the item and if they want another one after return they're probably just going to exchange it because something is wrong with it. It's not even a sale and I'm skeptical that seeing the ad has a strong influence on whether a customer asks for a refund or a replacement. ML is not some holy grail that always produces optimum algorithms. It depends heavily on inputs and on the assumptions, both explicit and implicit in the training data. My guess is Amazon does not have a "single-purchase item" model and it's not something the AI was trained to identify and so they aren't specifically excluded from groups of "similar-or-same" items. I think it is far more likely that Amazon is optimizing the cost of development against the marginal benefit of not showing ads for single-purchase items than that this is somehow driving more sales.
      - grandmczeb 6y ago
        I’ve personally done the following: 1. Buy a large ticket item (e.g. furniture). 2. See an ad on Amazon for a different/nicer/better/faster shipped version. 3. Buy it. 4. Cancel the old order. Is that a common pattern? No idea. But it’s not crazy to me that it happens often enough that it’s worth it to Amazon to show similar items to people who already bought them.
    - danaris 6y ago
      I mean, sure, I don't have any scientific studies to back this up. But I really don't feel like this is a case where "intuition might be completely wrong" applies—buying a $400 grill, and then just going back and buying 3 more $3-500 grills, just isn't something that people do on a regular basis. Same for vacuum cleaners, refrigerators, etc. And yet Amazon does regularly advertise these things to us after such large purchases. The only logical conclusion is that it's cheaper for them (in the short term, at least) not to update their ad/recommendation algorithm to take into account the nature of large one-time purchases.

frogpelt 6y ago

Would you say the majority of people shop like that? It makes sense to me that if I buy post hole diggers you should show me ads for work gloves or mailboxes or fences. Not more post hole diggers. Weird example, I know.

grandmczeb 6y ago
I mean, I’ve definitely done it and I’ve seen other people do it. I have no idea how typical it is.
jacobr1 6y ago
That would probably be a better strategy. But if you are looking at a naive, single variable, a prior purchase is the greatest single predictor of future purchases. If you know nothing else about a person, the fact you purchased one post-hole digger makes it more likely you'll purchase another, as opposed to some random other internet denizen for which we know nothing. Having worked in email marketing analysis before, this effect was surprisingly robust across categories. It implies you are the kind of person that could use such a product - most people aren't.

marblessubtext 6y ago

I bought a quality vacuum from Amazon and then continued to be aggressively advertised vacuums for months (on Amazon still) while shopping for things that honestly I could have used some advertising for to let me know what even existed in the space. Seems like not a great strategy for any involved party. They never advertised bags for said vacuum...