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How Cambridge Analytica’s Facebook targeting model really worked

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Re: How Cambridge Analytica’s Facebook targeting model really worked

#131

Post by emodendroket »

vuln wrote: post #77
frozenlettuce wrote: post #66

Earlier quoted context omitted.

It became a "problem" because it helped Trump win.

This is exactly it. At least it stops the news from droning on and on about Russia. I thought Clinton spent large amounts of money on data and the Democrats admitted the data was bad or at least that was their excuse. How much did CA pay for this data? I still find it crazy that Trump campaign spent 30% of what Hillary did and still won. The Russians used 100k$ worth of ads to sway the election. This stuff doesn't t…

Yes, that's a good point. Russia, Cambridge Analytica... anything that allows people to feel like the Trump phenomenon is a nefarious foreign import rather than homegrown. I'm no fan of Trump, but I'm incredibly dismayed that all the Democrats have talked about since he was elected is "Russian meddling."

Re: How Cambridge Analytica’s Facebook targeting model really worked

#132

Post by emodendroket »

mistermann wrote: post #126
ikeyany wrote: post #115

Earlier quoted context omitted.

The admission by the company executive.

That's interesting. How would he know the degree to which he influenced the election? Believing any claims to somehow fact rather than plain old self-promotion seems rather naive, or am I missing something?

Even if we presume those sentiments are completely sincere and disinterested, I don't know why we should believe he is an authority on US elections whose claims can simply be accepted at face value.

Re: How Cambridge Analytica’s Facebook targeting model really worked

#133

Post by rhizome »

stochastic_monk wrote: post #128
rhizome wrote: post #125

Earlier quoted context omitted.

Is this basically a choice between .mp3 and .ogg, png vs jpg vs gif?

It’s kind of comparable. Regardless, I still think having the most relevant features already extracted is all they need to ask many of the questions they might want to. The point is that that’s still quite bad.

Right, I was just trying to confirm an analogy. It seems like this stuff is like a lossy codec for traits.

Re: How Cambridge Analytica’s Facebook targeting model really worked

#134

Post by [deleted] »

darawk wrote: post #83
anf wrote: post #80

Earlier quoted context omitted.

How do you know what CA trained on, or what's possible? Do you have qualifications in ML?

I know what they trained on because it's been reported on. They got around 50 million people's FB profiles, and a smaller subset's (300k, I think) personality test results. I use ML models every day in my work, and understand how they function. It is true that individuals information is probabilistically encoded into the parameters of the model. However, if the model is any good, the people they trained on's informat…

[deleted]

Re: How Cambridge Analytica’s Facebook targeting model really worked

#135

Post by anf »

darawk wrote: post #83
anf wrote: post #80

Earlier quoted context omitted.

How do you know what CA trained on, or what's possible? Do you have qualifications in ML?

I know what they trained on because it's been reported on. They got around 50 million people's FB profiles, and a smaller subset's (300k, I think) personality test results. I use ML models every day in my work, and understand how they function. It is true that individuals information is probabilistically encoded into the parameters of the model. However, if the model is any good, the people they trained on's informat…

> I know what they trained on because it's been reported on.

What reason do you have to think their data set consisted of only what has been reported?

How do you know anything about the models they used?

Re: How Cambridge Analytica’s Facebook targeting model really worked

#136

Post by anf »

spydum wrote: post #85
anf wrote: post #71

Earlier quoted context omitted.

> It's arguable whether they should be allowed to keep those insights, but there's no privacy risk there really. So if Google has distilled someone's emails over the years into "closeted homosexual with a deeply repressed leather fetish", that's not an invasion of their privacy as long as they throw away the source materials?

As long as they retain no data which could specifically identify the original person, yes. There is nothing wrong with building segmentation models as long as they aren't specific enough to identify a specific person. My concern would be, how granular is too granular? What if we added "and live in zip code 12355 and is registered Green Party"? This now gets eerily specific, and might be sufficient to identify an indi…

Why would they ever discard that? Why would there be a granularity where ML suddenly stops working? Why would you even stop at one model per person, instead of one model per mood, or modes of thought at different stress points?

Re: How Cambridge Analytica’s Facebook targeting model really worked

#137

Post by Bukhmanizer »

dmix wrote: post #116
joncp wrote: post #53

Earlier quoted context omitted.

It sure seems that way. It's almost as if Netflix is giving in to pressure from content owners (which now includes themselves) to downplay or even weaken their suggestions. First, they got rid of those wonderful ranked lists that made us love Netflix in the first place, replacing them with the much more opaque cover art carousel view. Then they started mixing in lower-ranked items into the carousel. Finally, they swi…

I've heard rumours that the internal backlash at Netflix against 5 star ratings happened with Amy Schumer's most recent comedy special which had thousands of 1 star reviews on Netflix. Which was one of their most expensive comedy productions and whose release coincided not long before the switch over to vague thumbs up/down. Note, the comedy special was similarly panned across the press and social media as being repe…

By "heard rumours" do you mean "read about it on Breitbart?".

http://www.breitbart.com/big-hollywood/2017/03/18/netflix-sc...

Notice that they're careful to say that they made the switch "amid" the special, not because of it. Also as far as I can tell, they have no actual data on the fact, and they're the only "newspaper" reporting it.

Re: How Cambridge Analytica’s Facebook targeting model really worked

#138

Post by mistermann »

emodendroket wrote: post #132
mistermann wrote: post #126

Earlier quoted context omitted.

That's interesting. How would he know the degree to which he influenced the election? Believing any claims to somehow fact rather than plain old self-promotion seems rather naive, or am I missing something?

Even if we presume those sentiments are completely sincere and disinterested, I don't know why we should believe he is an authority on US elections whose claims can simply be accepted at face value.

I would tend to agree.

It's often not hard to convince people of something they want to believe.

Re: How Cambridge Analytica’s Facebook targeting model really worked

#139

Post by sdfmxiid1 »

godelski wrote: post #18
rjurney wrote: post #5

Earlier quoted context omitted.

It's a hard problem but Netflix's model represents the state of the art in machine learning for recommendations. Still scared of the singularity? :)

Personally, I used to get substantially better results. It would suggest to me a movie I'd never seen before with a score above 90, I'd watch, and enjoy. Now I'm getting things like kids shows suggested to me. I double checked by history to make sure no one watched one on my account, but they keep popping up with high percentage. I also really like horror and get weird suggestions [1] for similar movies. After I watc…

The coverage of the Netflix ratings format switch has always been frustrating to me because what people are complaining about (you're not the only one; https://www.polygon.com/2017/4/7/15212718/netflix-rating-sys...) was predictable from the beginning.

I do research in this area and it's fairly well established that when you go from something like five points to two points with ratings, you throw away tons of information. There's diminishing returns with numbers of points, but as you go lower you lose information.

The "ratings don't matter because what you want is implicit signals from peoples' actual behavior" is also disingenous because the rating behavior is a behavior that's directly tied to the stimulus in question. Not saying that indirect behavioral correlates aren't useful, only that the rating is a very powerful, direct correlate that tends to be very specific. Going back to the topic of the thread, sure, all those Facebook likes are going to be useful in predicting how much you like a candidate, but you're sure as hell going to get a lot of information by just asking them "on a scale of 1 to 5, how much do you approve of X?"

Re: How Cambridge Analytica’s Facebook targeting model really worked

#140

Post by darawk »

stochastic_monk wrote: post #123
darawk wrote: post #120

Earlier quoted context omitted.

Precisely because it's more powerful, it doesn't encode the identifying information of the original data. Something like PCA likely would retain identifying characteristics (depending on how many low-rank vectors you drop).

Outside of the fact that they have identities for all of the people whose data they acquired, yes, it would be harder to reconstruct individual people with it than PCA because of the direct interpretability of its data.

They claim to have deleted that data. If they haven't deleted the data, then of course it's still an invasion of privacy. But the ML model really has nothing to do with it.
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