How Facebook Knows When Its Ads Influence Your Offline Purchases • Hacker News Board

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#31

Post by polynomial » Fri, Dec 12, 2014, 1:13 AM UTC

song wrote: post #27

And this is why I did not give my phone number to facebook and why I use a different email for everything. It's unfortunate that keeping one's privacy requires a lot of knowledge and work.

> It's unfortunate that keeping one's privacy requires a lot of knowledge and work.

I wonder if the more vexing problem is that the market for privacy solutions seems largely unproven at scale. While people seem to value privacy when polled individually, they seem to vote the other way as an aggregate body.

Smart privacy products could take the knowledge and work out of it, but will the market support them?

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#32

Post by prostoalex » Fri, Dec 12, 2014, 1:16 AM UTC

chiph wrote: post #12

Who gives their phone number to store clerks? "Sorry, it's unlisted."

Large department stores would frequently pitch a loyalty card that's then tied up to your profile, for a which a phone number is frequently a must.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#33

Post by jankassens » Fri, Dec 12, 2014, 1:21 AM UTC

dao- wrote: post #14

"It has happened to you, and it has probably happened more than once." Umm, no. Why on earth would I give my phone number or email address to random shops? This is crazy. I surely don't want merchants to contact me "about other stuff I might want to buy." This assumption sold as a certainty in this article is somewhat disturbing. Do others from the US feel the same way? (I'm from Germany. Different culture?)

Store memberships for points and rebates on products are really common here in the US. When you sign up for them, they ask for your email, phone number, address, etc.

Safeway, a big supermarket chain, does this to an extreme. Many of their products are "50% off" when you enter your phone number of your membership on checkout. (It really just brings it down to a normal price).

Nothing prevents you from using a fake number, but as far as I can tell, most people give a real number.

It's certainly a different culture in Germany. Media and people are a lot more concerned collection of data.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#34

Post by jfuhrman » Fri, Dec 12, 2014, 1:44 AM UTC

chestnut-tree wrote: post #21

Some commentators in this discussion question why anyone would give their phone number to shops when they make a purchase. Yet millions of people give their mobile phone number (and name, date-of-birth and gender) to Google when they sign up for a Google account. And yet the degree of tracking that Google can undertake is an order of magnitude greater than what any individual store can track. Does Google use your mob…

Google uses Android phones GPS location to track people's store visits.

http://digiday.com/platforms/google-tracking/

http://www.datadrivenbusiness.com/google-quietly-testing-off...

If you turn it off, things like Google Now stop working.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#35

Post by logicallee » Fri, Dec 12, 2014, 2:00 AM UTC

nly wrote: post #30

logicallee wrote: post #17

Earlier quoted context omitted.

No, no. Read my link :) The whole point is that the definition of 'zero-knowledge' is that (if you use a zero knowledge interactive protocol) you learn no further knowledge. You are right that the hash-passing is not zero-knowledge. Rather than just verify whether it's in a set, you've accidentally revealed a number. So if you have a set of phone numbers and I have 1 to check if it's in that set, then checking hashes…

Intersecting a set of observed identifiers against another set is an issue Moxie dealt with on the TextSecures blog[0] (for phone numbers at that). He evaluated some ZKP algorithms and basically concluded this problem is hard or impractical today. I imagine an ad/referral network has many of the same real time constraints and scalability issues. [0] https://whispersystems.org/blog/contact-discovery/

thanks - this was interesting. Some of the numbers are interesting. So, for example, he says to have ten million clients updating daily, he would need to sustain 40 MB 116 times every second. . . that's like 37120 megabit so if you pay $10 per megabit monthly, that's $371,200 per month. It's pretty bad. On the other hand you do have ten million users.

so the numbers are off, but they're not five orders of magnitude off. If we're going to service ten million users, we might have something of a hosting budget for it.

So while I believe the author that the current trade-offs aren't goods, clever academic mathematics might help in the future. Cryptography itself came from there.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#36

Post by idiotclock » Fri, Dec 12, 2014, 2:15 AM UTC

Is anyone else frightened the increasing efficiency of capitalism? Since when does user-experience depend on best fulfilling my consumer desires? Shouldn't I try to soften this impulse?

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#37

Post by oliyoung » Fri, Dec 12, 2014, 2:21 AM UTC

chiph wrote: post #12

Who gives their phone number to store clerks? "Sorry, it's unlisted."

I'd argue that any HN member (or even any 1/2 tech savvy consumer) isn't exactly their target market

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#38

Post by phkahler » Fri, Dec 12, 2014, 2:25 AM UTC

I see false positives. So last week I decided to do my first project that will use a Raspberry Pi. I googled around to the pi site, amazon, newegg, (gasp) radio shack, microcenter, etc... I figured out what I wanted to get but didn't put anything in any carts. So then Pi ads start showing up on Facebook. IIRC a Radio Shack Pi ad too. Whatever. But now when I buy one, is Facebook going to claim some responsibility for the sale? Because they honestly don't deserve it. I'm going to buy one anyway and I have not seen an ad for a place I didn't look already. While I often give a real store the business based on "I can get it on the way home" the price difference in this case is nuts. So NewEgg it will be and Facebook ads aren't going to influence that.

In this case, correlation does not indicate causation.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#39

Post by jeffchuber » Fri, Dec 12, 2014, 2:43 AM UTC

phkahler wrote: post #38

I see false positives. So last week I decided to do my first project that will use a Raspberry Pi. I googled around to the pi site, amazon, newegg, (gasp) radio shack, microcenter, etc... I figured out what I wanted to get but didn't put anything in any carts. So then Pi ads start showing up on Facebook. IIRC a Radio Shack Pi ad too. Whatever. But now when I buy one, is Facebook going to claim some responsibility for…

causation is implied on a population through test and control. causation and correlation for an individual is almost always impossible.

Re: How Facebook Knows When Its Ads Influence Your Offline Purchases

#40

Post by wdewind » Fri, Dec 12, 2014, 3:12 AM UTC

tzs wrote: post #26

gcb0 wrote: post #2

...aaand facebook starts to buy news pieces to justify their ad network. this is nothing more than a press-release for their atlas feature. A new low even for wired.

Odd. It seems unusual for a press release to include criticism from the EFF. How would the article have to have been written for you to not think it was a press release?

I feel like PG's submarine piece has really made HN's view of PR very black and white. There are a lot more gradations, and likely this is a piece that was pitched by Facebook and actually was moderately investigated by Wired. The worst journalists are copy pasting press releases, the best are finding their own stories, but the vast majority lie somewhere in between. And I'm not convinced there is anything wrong with that.