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title: Forget privacy: you’re terrible at targeting anyway url: https://apenwarr.ca/log/20190201 hash_url: abe583967c

Forget privacy: you're terrible at targeting anyway

I don't mind letting your programs see my private data as long as I get something useful in exchange. But that's not what happens.

A former co-worker told me once: "Everyone loves collecting data, but nobody loves analyzing it later." This claim is almost shocking, but people who have been involved in data collection and analysis have all seen it. It starts with a brilliant idea: we'll collect information about every click someone makes on every page in our app! And we'll track how long they hesitate over a particular choice! And how often they use the back button! How many seconds they watch our intro video before they abort! How many times they reshare our social media post!

And then they do track all that. Tracking it all is easy. Add some log events, dump them into a database, off we go.

But then what? Well, after that, we have to analyze it. And as someone who has analyzed a lot of data about various things, let me tell you: being a data analyst is difficult and mostly unrewarding (except financially).

See, the problem is there's almost no way to know if you're right. (It's also not clear what the definition of "right" is, which I'll get to in a bit.) There are almost never any easy conclusions, just hard ones, and the hard ones are error prone. What analysts don't talk about is how many incorrect charts (and therefore conclusions) get made on the way to making correct ones. Or ones we think are correct. A good chart is so incredibly persuasive that it almost doesn't even matter if it's right, as long as what you want is to persuade someone... which is probably why newpapers, magazines, and lobbyists publish so many misleading charts.

But let's leave errors aside for the moment. Let's assume, very unrealistically, that we as a profession are good at analyzing things. What then?

Well, then, let's get rich on targeted ads and personalized recommendation algorithms. It's what everyone else does!

Or do they?

The state of personalized recommendations is surprisingly terrible. At this point, the top recommendation is always a clickbait rage-creating article about movie stars or whatever Trump did or didn't do in the last 6 hours. Or if not an article, then a video or documentary. That's not what I want to read or to watch, but I sometimes get sucked in anyway, and then it's recommendation apocalypse time, because the algorithm now thinks I like reading about Trump, and now everything is Trump. Never give positive feedback to an AI.

This is, by the way, the dirty secret of the machine learning movement: almost everything produced by ML could have been produced, more cheaply, using a very dumb heuristic you coded up by hand, because mostly the ML is trained by feeding it examples of what humans did while following a very dumb heuristic. There's no magic here. If you use ML to teach a computer how to sort through resumes, it will recommend you interview people with male, white-sounding names, because it turns out that's what your HR department already does. If you ask it what video a person like you wants to see next, it will recommend some political propaganda crap, because 50% of the time 90% of the people do watch that next, because they can't help themselves, and that's a pretty good success rate.

(Side note: there really are some excellent uses of ML out there, for things traditional algorithms are bad at, like image processing or winning at strategy games. That's wonderful, but chances are good that your pet ML application is an expensive replacement for a dumb heuristic.)

Someone who works on web search once told me that they already have an algorithm that guarantees the maximum click-through rate for any web search: just return a page full of porn links. (Someone else said you can reverse this to make a porn detector: any link which has a high click-through rate, regardless of which query it's answering, is probably porn.)

Now, the thing is, legitimate-seeming businesses can't just give you porn links all the time, because that's Not Safe For Work, so the job of most modern recommendation algorithms is to return the closest thing to porn that is still Safe For Work. In other words, celebrities (ideally attractive ones, or at least controversial ones), or politics, or both. They walk that line as closely as they can, because that's the local maximum for their profitability. Sometimes they accidentally cross that line, and then have to apologize or pay a token fine, and then go back to what they were doing.

This makes me sad, but okay, it's just math. And maybe human nature. And maybe capitalism. Whatever. I might not like it, but I understand it.

My complaint is that none of the above had anything to do with hoarding my personal information.

The hottest recommendations have nothing to do with me

Let's be clear: the best targeted ads I will ever see are the ones I get from a search engine when it serves an ad for exactly the thing I was searching for. Everybody wins: I find what I wanted, the vendor helps me buy their thing, and the search engine gets paid for connecting us. I don't know anybody who complains about this sort of ad. It's a good ad.

And it, too, had nothing to do with my personal information!

Google was serving targeted search ads decades ago, before it ever occurred to them to ask me to log in. Even today you can still use every search engine web site without logging in. They all still serve ads targeted to your search keyword. It's an excellent business.

There's another kind of ad that works well on me. I play video games sometimes, and I use Steam, and sometimes I browse through games on Steam and star the ones I'm considering buying. Later, when those games go on sale, Steam emails me to tell me they are on sale, and sometimes then I buy them. Again, everybody wins: I got a game I wanted (at a discount!), the game maker gets paid, and Steam gets paid for connecting us. And I can disable the emails if I want, but I don't want, because they are good ads.

But nobody had to profile me to make that happen! Steam has my account, and I told it what games I wanted and then it sold me those games. That's not profiling, that's just remembering a list that I explicitly handed to you.

Amazon shows a box that suggests I might want to re-buy certain kinds of consumable products that I've bought in the past. This is useful too, and requires no profiling other than remembering the transactions we've had with each other in the past, which they kinda have to do anyway. And again, everybody wins.

Now, Amazon also recommends products like the ones I've bought before, or looked at before. That's, say, 20% useful. If I just bought a computer monitor, and you know I did because I bought it from you, then you might as well stop selling them to me. But for a few days after I buy any electronics they also keep offering to sell me USB cables, and they're probably right. So okay, 20% useful targeting is better than 0% useful. I give Amazon some credit for building a useful profile of me, although it's specifically a profile of stuff I did on their site and which they keep to themselves. That doesn't seem too invasive. Nobody is surprised that Amazon remembers what I bought or browsed on their site.

Worse is when (non-Amazon) vendors get the idea that I might want something. (They get this idea because I visited their web site and looked at it.) So their advertising partner chases me around the web trying to sell me the same thing. They do that, even if I already bought it. Ironically, this is because of a half-hearted attempt to protect my privacy. The vendor doesn't give information about me or my transactions to their advertising partner (because there's an excellent chance it would land them in legal trouble eventually), so the advertising partner doesn't know that I bought it. All they know (because of the advertising partner's tracker gadget on the vendor's web site) is that I looked at it, so they keep advertising it to me just in case.

But okay, now we're starting to get somewhere interesting. The advertiser has a tracker that it places on multiple sites and tracks me around. So it doesn't know what I bought, but it does know what I looked at, probably over a long period of time, across many sites.

Using this information, its painstakingly trained AI makes conclusions about which other things I might want to look at, based on...

...well, based on what? People similar to me? Things my Facebook friends like to look at? Some complicated matrix-driven formula humans can't possibly comprehend, but which is 10% better?

Probably not. Probably what it does is infer my gender, age, income level, and marital status. After that, it sells me cars and gadgets if I'm a guy, and fashion if I'm a woman. Not because all guys like cars and gadgets, but because some very uncreative human got into the loop and said "please sell my car mostly to men" and "please sell my fashion items mostly to women." Maybe the AI infers the wrong demographic information (I know Google has mine wrong) but it doesn't really matter, because it's usually mostly right, which is better than 0% right, and advertisers get some mostly demographically targeted ads, which is better than 0% targeted ads.

You know this is how it works, right? It has to be. You can infer it from how bad the ads are. Anyone can, in a few seconds, think of some stuff they really want to buy which The Algorithm has failed to offer them, all while Outbrain makes zillions of dollars sending links about car insurance to non-car-owning Manhattanites. It might as well be a 1990s late-night TV infomercial, where all they knew for sure about my demographic profile is that I was still awake.

You tracked me everywhere I go, logging it forever, begging for someone to steal your database, desperately fearing that some new EU privacy regulation might destroy your business... for this?

Statistical Astrology

Of course, it's not really as simple as that. There is not just one advertising company tracking me across every web site I visit. There are... many advertising companies tracking me across every web site I visit. Some of them don't even do advertising, they just do tracking, and they sell that tracking data to advertisers who supposedly use it to do better targeting.

This whole ecosystem is amazing. Let's look at online news web sites. Why do they load so slowly nowadays? Trackers. No, not ads - trackers. They only have a few ads, which mostly don't take that long to load. But they have a lot of trackers, because each tracker will pay them a tiny bit of money to be allowed to track each page view. If you're a giant publisher teetering on the edge of bankruptcy and you have 25 trackers on your web site already, but tracker company #26 calls you and says they'll pay you $50k a year if you add their tracker too, are you going to say no? Your page runs like sludge already, so making it 1/25th more sludgy won't change anything, but that $50k might.

("Ad blockers" remove annoying ads, but they also speed up the web, mostly because they remove trackers. Embarrassingly, the trackers themselves don't even need to cause a slowdown, but they always do, because their developers are invariably idiots who each need to load thousands of lines of javascript to do what could be done in two. But that's another story.)

Then the ad sellers, and ad networks, buy the tracking data from all the trackers. The more tracking data they have, the better they can target ads, right? I guess.

The brilliant bit here is that each of the trackers has a bit of data about you, but not all of it, because not every tracker is on every web site. But on the other hand, cross-referencing individuals between trackers is kinda hard, because none of them wants to give away their secret sauce. So each ad seller tries their best to cross-reference the data from all the tracker data they buy, but it mostly doesn't work. Let's say there are 25 trackers each tracking a million users, probably with a ton of overlap. In a sane world we'd guess that there are, at most, a few million distinct users. But in an insane world where you can't prove if there's an overlap, it could be as many as 25 million distinct users! The more tracker data your ad network buys, the more information you have! Probably! And that means better targeting! Maybe! And so you should buy ads from our network instead of the other network with less data! I guess!

None of this works. They are still trying to sell me car insurance for my subway ride.

It's not just ads

That's a lot about profiling for ad targeting, which obviously doesn't work, if anyone would just stop and look at it. But there are way too many people incentivized to believe otherwise. Meanwhile, if you care about your privacy, all that matters is they're still collecting your personal information whether it works or not.

What about content recommendation algorithms though? Do those work?

Obviously not. I mean, have you tried them. Seriously.

That's not quite fair. There are a few things that work. Pandora's music recommendations are surprisingly good, but they are doing it in a very non-obvious way. The obvious way is to take the playlist of all the songs your users listen to, blast it all into an ML training dataset, and then use that to produce a new playlist for new users based on... uh... their... profile? Well, they don't have a profile yet because they just joined. Perhaps based on the first few songs they select manually? Maybe, but they probably started with either a really popular song, which tells you nothing, or a really obscure song to test the thoroughness of your library, which tells you less than nothing.

(I'm pretty sure this is how Mixcloud works. After each mix, it tries to find the "most similar" mix to continue with. Usually this is someone else's upload of the exact same mix. Then the "most similar" mix to that one is the first one, so it does that. Great job, machine learning, keep it up.)

That leads us to the "random song followed by thumbs up/down" system that everyone uses. But everyone sucks, except Pandora. Why? Apparently because Pandora spent a lot of time hand-coding a bunch of music characteristics and writing a "real algorithm" (as opposed to ML) that tries to generate playlists based on the right combinations of those characteristics.

In that sense, Pandora isn't pure ML. It often converges on a playlist you'll like within one or two thumbs up/down operations, because you're navigating through a multidimensional interconnected network of songs that people encoded the hard way, not a massive matrix of mediocre playlists scraped from average people who put no effort into generating those playlists in the first place. Pandora is bad at a lot of things (especially "availability in Canada") but their music recommendations are top notch.

Just one catch. If Pandora can figure out a good playlist based on a starter song and one or two thumbs up/down clicks, then... I guess it's not profiling you. They didn't need your personal information either.


While we're here, I just want to rant about Netflix, which is an odd case of starting off with a really good recommendation algorithm and then making it worse on purpose.

Once upon a time, there was the Netflix prize, which granted $1 million to the best team that could predict people's movie ratings, based on their past ratings, with better accuracy than Netflix could themselves. (This not-so-shockingly resulted in a privacy fiasco when it turned out you could de-anonymize the data set that they publicly released, oops. Well, that's what you get when you long-term store people's personal information in a database.)

Netflix believed their business depended on a good recommendation algorithm. It was already pretty good: I remember using Netflix around 10 years ago and getting several recommendations for things I would never have discovered, but which I turned out to like. That hasn't happened to me on Netflix in a long, long time.

As the story goes, once upon a time Netflix was a DVD-by-mail service. DVD-by-mail is really slow, so it was absolutely essential that at least one of this week's DVDs was good enough to entertain you for your Friday night movie. Too many Fridays with only bad movies, and you'd surely unsubscribe. A good recommendation system was key. (I guess there was also some interesting math around trying to make sure to rent out as much of the inventory as possible each week, since having a zillion copies of the most recent blockbuster, which would be popular this month and then die out next month, was not really viable.)

Eventually though, Netflix moved online, and the cost of a bad recommendation was much less: just stop watching and switch to a new movie. Moreover, it was perfectly fine if everyone watched the same blockbuster. In fact, it was better, because they could cache it at your ISP and caches always work better if people are boring and average.

Worse, as the story goes, Netflix noticed a pattern: the more hours people watch, the less likely they are to cancel. (This makes sense: the more hours you spend on Netflix, the more you feel like you "need" it.) And with new people trying the service at a fixed or proportional rate, higher retention translates directly to faster growth.

When I heard this was also when I learned the word "satisficing," which essentially means searching through sludge not for the best option, but for a good enough option. Nowadays Netflix isn't about finding the best movie, it's about satisficing. If it has the choice between an award-winning movie that you 80% might like or 20% might hate, and a mainstream movie that's 0% special but you 99% won't hate, it will recommend the second one every time. Outliers are bad for business.

The thing is, you don't need a risky, privacy-invading profile to recommend a mainstream movie. Mainstream movies are specially designed to be inoffensive to just about everyone. My Netflix recommendations screen is no longer "Recommended for you," it's "New Releases," and then "Trending Now," and "Watch it again."

As promised, Netflix paid out their $1 million prize to buy the winning recommendation algorithm, which was even better than their old one. But they didn't use it, they threw it away.

Some very expensive A/B testers determined that this is what makes me watch the most hours of mindless TV. Their revenues keep going up. And they don't even need to invade my privacy to do it.

Who am I to say they're wrong?