It would be intriguing to see Amazon's stats about how often people buy after receiving these emails. They must work, I've just got no idea how successful they

It would be intriguing to see Amazon's stats about how often people buy after receiving these emails. They must work, I've just got no idea how successful they are. Would anyone care to guess what % of these kind of messages trigger a sale? Similarly, It'd be interesting to see stats on other forms of 'reminder' advertising. Like the type that keep showing you recently viewed products as you browse other websites. I'd have thought this would just be irritating to people, but again, it probably works because companies keep doing it. Are there any public stats about how effective it is?