Well it might be true for certain products. But I find it funny how they recommend me my phone or my laptop. Those aren't things you usually buy in bulk.
> Here's a true statement: People who will in 2018 give birth to a child named Abigail are at least 5X more likely to give birth to a child in 2019 than people chosen at random.
> "Naming your child Abigail can't make you more likely to get pregnant."
> Again, failure to do the math.
> (You get a 2X there, for free, from the observation "If you had a child named Abigail this year you are biologically capable of having children; this is not true of no less than half of humanity. Now apply same insight to childbearing age and you're already at 5X+.)
This is terrible math. Nursing a child severely inhibits getting pregnant; without use of formula (or a substitute like goat's milk or what have you), it is extremely rare for children to be spaced only one year apart. It's rare enough that there's a special term for such children -- "Irish twins".
If you want to swagger your conditional probability, you should know that you've got to account for that in the probability of giving birth one year given that you gave birth the year before. You can't just account for the positive adjustments, ignore the negative ones, and then say "the odds are at least as good as they would be if the existing anticorrelations didn't exist".
> What's a SWAG for how often a purchase immediately goes wrong? Not right color? Fridge DOA? Shoot I mismeasured my kitchen? Wife just hates it? Call that 2%. If I fix it within a week, then 2% / 7 = 2.9e-3 probability of purchasing a new fridge.
> That's a 10X relative risk.
But of those listed options for "immediately goes wrong", zero of them would result in re-buying the same fridge. Wrong color, I mismeasured my kitchen, and wife hates it would cause you to buy a different fridge. Fridge DOA would cause you to refund the fridge and get a replacement.
How many people, faced with the expense of a fridge that hasn't worked out, figure the best course is to just write it off and buy a second copy, hoping that it will work out better?
> This is terrible math. Nursing a child severely inhibits getting pregnant; without use of formula (or a substitute like goat's milk or what have you), it is extremely rare for children to be spaced only one year apart. It's rare enough that there's a special term for such children -- "Irish twins".
The timespan for two separate births in 2018 and 2019 isn't 12 months, it is anywhere between 12 and 24 months. While giving birth twice in 12 months is rare, I would assume that giving birth twice in 18 months or 24 months is not nearly as rare.
Yes, giving birth twice in 24 months is normal, but that gives you a very narrow window within 2018/2019.
If you give birth in July of 2018, an 18 month spacing won't let you give birth in any month of 2019. That's still a very significant negative adjustment to "demographic factors get you to 5X+". Demographic factors aren't the only factors there are.
This is the birth rate (for 2016, in the US) reflecting the odds that a randomly-selected person, male, female, infant, or menopausal, will give birth in a calendar year.
> Fertility rate: 62.0 births per 1,000 women aged 15-44
And this is the birth rate demographically adjusted for the ability to give birth. It's about five times higher.
Since siblings born in consecutive calendar years are rare, we can only conclude that patio11's "true statement" is false by a pretty large margin. For it to be true, every birth in 2016 would have to have been to a woman who also gave birth in 2015.
I wish that, before asserting something is true, people would think about whether it's true.
> we can only conclude that patio11's "true statement" is false by a pretty large margin. For it to be true, every birth in 2016 would have to have been to a woman who also gave birth in 2015.
So this has been bothering me, because if every birth in one year is to a woman who gave birth the previous year, and the years have equal birth rates, and we ignore aging in/out of the "fertile" demographic, then the odds of giving birth in one year given that you gave birth last year are 100%, well over 5x the population rate.
The claim is that the odds of giving birth this year given you gave birth last year are equal to the odds of giving birth this year given you're fertile, or in other words that, if you're fertile, whether you give birth this year is probabilistically independent of whether you gave birth last year. This is quite clearly false -- your odds of giving birth in one year are much lower, given you gave birth the year before, than your odds of giving birth in any randomly-selected year during which you're fertile. But my argument above is wrong.
For patio11's claim to be true, 6.1% of women who gave birth in one year would need to give birth again the next year. (Stated equivalently, 6.1% of people would need to have an older sibling born one calendar year before themselves.)
Good call with that sanity check. Patio11's assertion definitely had that paradoxical lightbulb moment that makes you want to believe it is true (a la Malcolm Gladwell), but two data points were all that was necessary to expose it.
The refrigerator example is stupid. I'm talking about buying something from Amazon, so if I have buyer's remorse or it's broken I won't ever buy that model of the same thing again from Amazon. I would at most return it, which the ad might remind me of.
There's a certain truth to you being in that buyer's class now, because there is a certain population that buys laptops. Yet as he stated, I'm not in the buying cycle. I would probably be in the buying cycle again in 1-2-3-4-5 years from now. So immediately advertising for something you buy rarely (refrigerators more, laptops less, phones maybe more often) is still wasted ad space.
David Scotten's comment on that thread is a bit more on point: "There's the opportunity cost of not showing another ad in that slot, though. So they're showing you what they think is the ad with the highest expected value for them."
I think they don't calculate the opportunity cost right. They will advertise right away for something that is unlikely in their best slot in my emails.
It would be better for them to advertise other related electronics (headphones that work with bluetooth if you just bought a new phone with bluetooth, loudspeakers, computer screen, external keyboard, docking station, etc.) Those would actually be much more likely buys for me.
Funny actually how babies are mentioned. I never had a baby, nor do I have a girlfriend (something Amazon should probably know with some basic data science), yet they always advertise baby diapers to me, even to the point of sending me some as advertisement. I still can't figure out how that happened.
For me Amazon is a store where I always look for something specific. Only the book recommendations have really made me buy something I didn't think of before. I think there's a lot of lost potential here for Amazon.
