> the problem is that the signal is just so robust. That's why you aren't seeing the better solution. You're only seeing what you know, which is the (tired o

> the problem is that the signal is just so robust. That's why you aren't seeing the better solution. You're only seeing what you know, which is the (tired old) signal you know how to detect. But you already detected it, and monetised it. A better recommendation signal would be the one that you don't know how to detect. It's the signal people get unexpectedly from other people, when they chat about the thing they just bought. Call it the n+1 recommendation signal. > The fact that you bought a ladder, puts you in the cohort of people that buys ladders, which means you are more likely to buy another one than someone who isn't on the record buying a ladder. OK, but that's still the n recommendation signal, which has already been monetised, and won't be refreshed for quite some time, in the same way a Venus fly trap takes time before it will open and trigger again. What can a person do with a ladder that she couldn't do before? That question is what begets the n+1 recommendation signal. It isn't a question that even gets asked explicitly. It happens through association. She says "I got a new ladder, and a paintbrush and some paint." and her friend says, "Oh great, I just used my ladder to hang a bird feeder from the sycamore tree!" and then she says "Oh! I've got a sycamore tree too! Where'd you get your bird feeder?"