How Cambridge Analytica’s Facebook targeting model really worked • Hacker News Board

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

#171

Post by mistermann » Sat, Mar 31, 2018, 2:03 PM UTC

pjc50 wrote: post #165

mistermann wrote: post #105

Earlier quoted context omitted.

It doesn't have to add up, most people are too busy with their real lives to manually search and find reliable details (what we get from the media is not reliably unbiased or true), and then read and understand them, so they believe what they see and hear repeated over and over on the TV, radio, and newspaper: the American President is controlled by Vladimir Putin. Even most smart people don't seem to care about actu…

We can freely infer things just from reading his own Twitter feed. Such as the silence of the Salisbury poisoning vs. the instant reaction to other UK terrorist incidents.

From this you infer that he is under the control of Putin? He is pro Russia no doubt, but I don't think that is what's being asserted by the media. I'd prefer they stick to facts, do you disagree?

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

#172

Post by [deleted] » Sat, Mar 31, 2018, 2:40 PM UTC

darawk wrote: post #68

etiam wrote: post #41

Spoiler warning. Article punchline ahead. "The whole point of a dimension reduction model is to mathematically represent the data in simpler form. It’s as if Cambridge Analytica took a very high-resolution photograph, resized it to be smaller, and then deleted the original. The photo still exists — and as long as Cambridge Analytica’s models exist, the data effectively does too." That's an eloquent piece of explanati…

> when strictly speaking the raw data has indeed been deleted after being used to create a derivative work that can for all important purposes be used to recreate the original? To be precise, you almost certainly cannot use this data to recreate anything remotely resembling the original dataset. This type of dimensionality reduction would throw away enormous volumes of data. There is no meaningful sense in which you…

[deleted]

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

#173

Post by emodendroket » Sat, Mar 31, 2018, 2:50 PM UTC

mistermann wrote: post #171

pjc50 wrote: post #165

Earlier quoted context omitted.

We can freely infer things just from reading his own Twitter feed. Such as the silence of the Salisbury poisoning vs. the instant reaction to other UK terrorist incidents.

From this you infer that he is under the control of Putin? He is pro Russia no doubt, but I don't think that is what's being asserted by the media. I'd prefer they stick to facts, do you disagree?

He's "pro-Russia" in the sense that he seems to have some sort of admiration for Putin's tough-guy persona, but I can't see much other sense in which that's meaningfully true.

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

#174

Post by pohl » Sat, Mar 31, 2018, 2:51 PM UTC

darawk wrote: post #140

stochastic_monk wrote: post #123

Earlier quoted context omitted.

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.

The ML model might know more about me than I’m willing to admit about myself. I only find some — but not much — comfort in the proposition that it can’t conjure my PII.

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

#175

Post by [deleted] » Sat, Mar 31, 2018, 3:30 PM UTC

etiam wrote: post #41

Spoiler warning. Article punchline ahead. "The whole point of a dimension reduction model is to mathematically represent the data in simpler form. It’s as if Cambridge Analytica took a very high-resolution photograph, resized it to be smaller, and then deleted the original. The photo still exists — and as long as Cambridge Analytica’s models exist, the data effectively does too." That's an eloquent piece of explanati…

[deleted]

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

#176

Post by kurthr » Sat, Mar 31, 2018, 3:35 PM UTC

etiam wrote: post #41

Spoiler warning. Article punchline ahead. "The whole point of a dimension reduction model is to mathematically represent the data in simpler form. It’s as if Cambridge Analytica took a very high-resolution photograph, resized it to be smaller, and then deleted the original. The photo still exists — and as long as Cambridge Analytica’s models exist, the data effectively does too." That's an eloquent piece of explanati…

Based on that description I'd say it's closer to taking a RAW format and converting it into a JPG, which contains most of the (human visual) relevant data from a DCT while removing the remaining "noise"... which is a bit different from simply resizing (eg subsampling). What I would find a bit satisfying about this description is that you probably wouldn't get away with claiming that a JPG of an image was un-copyrighted and only a BMP (of the same resolution) was.

To be fair, it does depend on the amount of compression before it is not recognizable, but if you can still squint and see the Mona Lisa (when you also have her phone #)... have you not violated her privacy?

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

#177

Post by kurthr » Sat, Mar 31, 2018, 3:45 PM UTC

darawk wrote: post #68

etiam wrote: post #41

Spoiler warning. Article punchline ahead. "The whole point of a dimension reduction model is to mathematically represent the data in simpler form. It’s as if Cambridge Analytica took a very high-resolution photograph, resized it to be smaller, and then deleted the original. The photo still exists — and as long as Cambridge Analytica’s models exist, the data effectively does too." That's an eloquent piece of explanati…

> when strictly speaking the raw data has indeed been deleted after being used to create a derivative work that can for all important purposes be used to recreate the original? To be precise, you almost certainly cannot use this data to recreate anything remotely resembling the original dataset. This type of dimensionality reduction would throw away enormous volumes of data. There is no meaningful sense in which you…

So if I compress a BMP by 100:1 using "lossy" techniques then it's not equivalent to the original? I'd say that depends on how recognizable the result of reconstruction is, and not on the amount of reduction. MPAA would be very unhappy with your argument.

To be more extreme there are many compression/extraction methods that can perfectly reconstruct the original data with very high compression ratios. GIF/PNG can reproduce many images exactly. Certainly, they are derivative works?

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

#178

Post by learnstats2 » Sat, Mar 31, 2018, 3:53 PM UTC

MattyRad wrote: post #81

ikeyany wrote: post #40

Earlier quoted context omitted.

Who said anything about a security breach? Most of the controversy has been about the company influencing elections using data scraped from people (and their friends) unaware of what the data was being used for.

The degree to which it influenced the election is questionable. Despite all the headlines, I haven't yet seen any convincing analysis of the impact of facebook on the election (I'm not sure how one would even go about doing so). So far it seems like it's just a convenient vehicle for people that dislike the outcome of the election to express indignation.

This is obviously unmeasurable - there isn't convincing analysis because there can't be convincing analysis, as you admit.

The fact that people were willing to spend an amount of money that breached electoral law in the UK, and presumably even more in the US, suggests that there was some reason for them to do so. This happened only because experts in this field believed it would influence the outcome of the election.

That's your evidence.

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

#179

Post by SlowRobotAhead » Sat, Mar 31, 2018, 4:14 PM UTC

majormajor wrote: post #73

frenchie14 wrote: post #59

Earlier quoted context omitted.

Outside of the tech bubble, simply saying "yes" would be disingenuous. They're not even asking the question in the first place

I think retargeting has thoroughly blown up the idea that ads online are shown to everyone. My non-technical acquaintances are very aware of why certain products follow them around the internet in ads.

Agreed. Although we all hate it, if my mom searches for hard sided luggage on amazon and ads for it follow her to all manner of other sites - that’s the best way for non-tech types to get some of the idea here.

The truth is WAY worse of course, but she immediately knows the ads she saw won’t show for me as well.

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

#180

Post by vanilla_nut » Sat, Mar 31, 2018, 4:56 PM UTC

godelski wrote: post #4

> has revealed that his method worked much like the one Netflix uses to recommend movies. I'm not sure this is the model you want to emulate. The suggestions are terrible and continually getting worse.

In my anecdotal experience, it seems like Netflix's own content gets weighed disproportionately high. This could be a result of the fact that first-party content never gets removed, so it builds up a more complex graph of recommendations, but personally it feels like they're trying way too hard to cram their content down my throat -- to a point of recommending shows that I would never even consider watching, like Jane the Virgin (not exactly my kind of humor). In the end it just feels like they've compromised their own recommendations to push their own product, which makes me mistrust all of their recommendations.