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A few weeks ago, the Proceedings of the National Academy of Science published an article on a study conducted by a group of Cornell researchers at Facebook. They picked about 600,000 users and then, for a week, a subset of them saw fewer “negative” posts (up to 90% were filtered) than they would otherwise see, a subset saw fewer “positive” posts (same), and a control group got a random subset.
After the week, the users in the “negative” group posted fewer, and more negative, posts, and those in the “positive” group posted more, and more positive, posts.
Posts were classified according to an algorithm called LIWC2007.
The study run contrary to a conventional wisdom that people find it depressing to see on Facebook good things happening to their friends.
The paper has caused considerable controversy for being a study with human subjects conducted without explicit consent. Every university, including of course Cornell, requires experiments involving people to be approved by a special committee, and participants must sign informed consent forms. Facebook maintains that the study is consistent with its terms of service. The highly respected privacy organization EPIC has filed a complaint with the FTC. (And they have been concerned with Facebook’s term of service for a long time.)
Here I would like to explore a different angle: almost everybody thinks that observational studies about human behavior can be done without informed consent. This means that if the Cornell scientists had run an analysis on old Facebook data, with no manipulation of the feed generation algorithm, there would not have been such a concern.
At the same time, the number of posts that are fit for the feed of a typical user vastly exceed what can fit in one screen, and so there are algorithms that pick a rather small subset of posts that are evaluated to be of higher relevance, according to some scoring function. Now suppose that, if N posts fit on the screen, the algorithm picks the 2N highest scoring posts, and then randomly picks half of them. This seems rather reasonable because the scoring function is going to be an approximation of relevance anyway.
The United States has roughly 130 million Facebook subscriber. Suppose that the typical user looks, in a week, at 200 posts, which seems reasonable (in our case, those would be a random subset of roughly 400 posts). According to the PNAS study, roughly 50% of the posts are positive and 25% are negative, so of the initial 400, roughly 200 are positive and 100 are negative. Let’s look at the 100,000 users for which the random sampling picked the fewest positive posts: we would be expecting roughly 3 standard deviations below the mean, so about 80 positive posts instead of the expected 100; the 100,000 users with the fewest negative posts would get about 35 instead of the expected 50.
This is much less variance than in the PNAS study, where they would have got, respectively, only 10 positive and only 5 negative, but it may have been enough to pick up a signal.
Apart from the calculations, which I probably got wrong anyway, what we have is that in the PNAS study they picked a subset of people and then they varied the distribution of posts, while in the second case you pick random posts for everybody and then you select the users with the most variance.
If you could arrange distributions so that the distributions of posts seen by each users are the same, would it really be correct to view one study as experimental and one as observational? If the PNAS study had filtered 20% instead of 90% of the positive/negative posts, would it have been ethical? Does it matter what is the intention when designing the randomized algorithm that selects posts? If Facebook were to introduce randomness in the scoring algorithm with the goal of later running observational studies would it be ethical? Would they need to let people opt out? I genuinely don’t know the answer to these questions, but I haven’t seen them discussed elsewhere.
Here is the call for applications, from the official Italian web site of the Ministry for Education and Research, for a postdoctoral fellowship on a project titled “‘Dalla pecora al pecorino’ tracciabilità e rintracciabilità di filiera nel settore lattiero caseario toscano”, which roughly translates to “From sheep to pecorino, traceability in the Tuscan dairy industry.”
The announcement has an English translation, and something got lost in translation, having to do to the fact that in Italy we say “sheep style” instead of “doggy style” (don’t ask).
Update 2/16/2012: the page has been updated, below is a screenshot before the update (click to expand)
David Willetts, the British minister for higher education, has recently announced that the government was “inviting proposals for a new type of university with a focus on science and technology and on postgraduates.” The NYT article on the matter may be biased, but it looks like this announcement could have come from the Italian ministry of university and research, and I mean it as an offense.
So, how much will the government invest in this new university? “There will be no additional government funding,” Mr. Willetss says, and all the funding will have to come from the private sector. And what is the government’s vision and plan for this new university? Mr. Willetts says that “We are not intending to issue any guidelines. We want people to come to us with ideas.”
So the idea of the minister for higher education is that the private sector comes up with all the funding and all the planning for a new university. (Imagine the home secretary stating the goal of increasing the police force, but all the new police force would be paid for by the private sector, which, after all, has an interest in reducing street crime, and that it is not the intention of the home office to dictate how this private police force should operate.) This is exactly what an Italian minister would talk about at a press conference, only to be forgotten the following week.
The reaction from the academia, however, is different. In Italy, you would see people throw their hands in the air and say “madonna mia, in mano a chi siamo,” while the British are masters of understatement.
“We at Oxford feel that keeping the U.K. a world leader in science and research is a very important objective,” Ian Walmsley, Oxford’s chief research officer, “and we’re pleased that the government agrees with that.”
Stephen Caddick, for the University College at London says the proposal is “not uninteresting”.
From an interview with Ed Mango, head of NASA’s commercial crew program, in which he discusses safety requirements for commercial entities who want to subcontract flights to the ISS from NASA.
Chaikin: And the probability of “loss of crew” has to be better than 1 in 1000?
Mango: Yes and no. What we’ve done is we’ve separated those into what you need for ascent and what you need for entry. For ascent it’s 1 in 500, and independently for entry it’s 1 in 500. We don’t want industry … to [interpret the 1-in-1,000 requirement] to say, “We’ve got a great ascent; we don’t need as much descent protection.” In reality we’ve got to protect the life of the crew all the time.
Now [the probability for] the mission itself is 1 in 270. That is an overall number. That’s loss of crew for the entire mission profile, including ascent, on-orbit, and entry. The thing that drives the 1 in 270 is really micrometeorites and orbital debris … whatever things that are in space that you can collide with. So that’s what drops that number down, because you’ve got to look at the 210 days, the fact that your heat shield or something might be exposed to whatever that debris is for that period of time. NASA looks at Loss of Vehicle the same as Loss of Crew. If the vehicle is damaged and it may not be detected prior to de-orbit, then you have loss of crew.
What does “yes” mean in the “yes and no” answer? Also, with a 1/500 probability of accident at takeoff and an independent 1/500 probability of accident at landing, we are already at a 1/250.2 probability of accident, so how do we get to 1/270 after adding accidents in mid-flight?
In not entirely unrelated news, a member of the board of Florida’s 3rd district took, and failed, the Florida Comprehensive Assessment Test (FCAT), a standardized test, as documented in two posts on the Washington Post blog.
“I won’t beat around the bush. The math section had 60 questions. I knew the answers to none of them, but managed to guess ten out of the 60 correctly. On the reading test, I got 62% . In our system, that’s a ‘D,’ and would get me a mandatory assignment to a double block of reading instruction.
“It seems to me something is seriously wrong. I have a bachelor of science degree, two masters degrees, and 15 credit hours toward a doctorate. I help oversee an organization with 22,000 employees and a $3 billion operations and capital budget, and am able to make sense of complex data related to those responsibilities….
Here is a sample of the math portion of the 10th grade FCAT, the most advanced one. Sample question: “An electrician charges a $45 fee to make a house call plus an hourly rate for labor. If the electrician works at one house for 3 hours and charges $145.50 for the job, what is the electrician’s hourly rate?” You can use a calculator.
From a 1977 interview with the late theoretical physicist Sidney Coleman.
Coleman: Teaching is unpleasant work. No question about it. It has its rewards. One feels happy about having a job well done. Washing the dishes, waxing the floors (things I also do on a regular basis since I’m a bachelor) have their rewards. I am pleased when I have done a good job waxing the floor and I’ve taken an enormous pile of dirty dishes and reduced them to sparkling clean ones. On the other hand, if I didn’t have to, I would never engage in waxing the floors, although I’m good at it. I’m also good at teaching; I’m considered very good at teaching, both by myself and others. And I’m also terrifically good at washing dishes, in fact. On the other hand, I certainly would never make a bunch of dirty dishes just for the joy of washing them and I would not teach a course just for the joy of teaching a course. (…) if someone were to suddenly say to me, look you can sit in this office and talk and do physics with the same people, everything would be the same except you would never have to teach a course and never have to see a graduate student, and we’ll halve your salary — I’d leap at the offer.
Sopka: So I guess really you would be happier with the format of an institute of theoretical physics? Rather than a teaching institution like a university?
Coleman: Well no. That makes it too abstract. Because that means, would you like to have a position at, say, the Institute for Advanced Studies? And then all sorts of other things would enter the picture. Like you’d have to live in Princeton which is truly an awful experience. (…) It’s a terrible place. Dullest place in the world. No I wouldn’t say that, but certainly the dullest place at which decent science or decent scholarship is done in the world today. The only advantage to Princeton is that it’s close to Princeton Junction.
A few days ago, the Royal Society released a report on “Global Scientific Collaboration in the 21st Century.” Usually, when a document has “in the 21st Century” in the title, it can only go downhill from there. (I once had to review a paper that started with “As we enter the second decade of the 21st Century…” and, hard as it is to believe, it did go further downhill from there.) But the Royal Society is one of the most hallowed of scientific institutions, so one might have still hoped for the best.
The report was widely quoted in the press as predicting that China would overtake the United States in scientific output by 2013.
Indeed, in Section 1.6 (pages 42-43), the report uses data provided by Elsevier to estimate the number of scientific papers produced in various countries. We’ll skip the objection that the number of papers is a worthless measure of scientific output and go to figure 1.6 in the report, reproduced below.
The figure plots the percentage of scientific papers coming out of various countries, and then proceeds to do a linear interpolation of the percentages to create a projection for the future.
While such an approach shows China overtaking the US in 2013, it also shows, more ominously, China publishing 110% of all scientific papers by 2100. (The report concedes that linear interpolation might not make a lot of sense, yet the picture is there.)
The New York times has an interesting article (read it while you can) about MIT’s effort in the past 10 year to tackle discrimination against women, initially in the School of Science and then over the entire university.
A recently released report points out the progress, as well as interesting problems that remain open. For example (the following sentence is not attributed and does not appear in quotes):
Despite an effort to educate colleagues about bias in letters of recommendation for tenure, those for men tend to focus on intellect while those for women dwell on temperament.
This is very interesting if true. In principle, it is a testable assertion: one could take a large sample of recommendation letter, remove all direct reference to gender (she/her/ first names, etc.), use half of them to train a machine learning algorithm, and then see if the algorithm is able to guess better than randomly which of the remaining letters are for women and which are for men. (Among other things, the learning algorithm would pick up a higher frequency of words about temperament, if such comments were really more frequent about women.)
The article also points out societal issues on which MIT has little control but that are important, for example the fact that child care and family-work balance are seen as women issues, rather than parents issue.
In a way, it is good that now these are the kind of issues that remain to be addressed, compared to the outright discrimination that was determined to have occurred in a mid-1990s review, and compared to what happens in other fields and/or in other institutions.
Meanwhile, Mark Krikorian, in National Review, writes that the United States intervened in Libya because the women in the administration “nagged” Obama into doing so, and Mr. Krikorian worries about what foreigners will think of us because of it. Note the classy title of his post.
Edited to add: the top two students in my class CS261 were both women.
While searching for the origin of the expression “biggest and baddest” (long story — by the way, I wasn’t able to find it), I came across the following books:
The titles seem already the imagined setup of a Simpsons episode in which Lisa is riled up against corporate sexism. (Remember the episode with the Malibu Stacy doll that says “math is hard, let’s go shopping,” which was based on a real Barbie doll?) The contents do not disappoint.
The biggest and baddest book (the table of contents can be read on Amazon) is all, more or less, encouraging interest in science, engineering, and even math: there are dinosaurs, DNA, how a cell phone works, how an MP3 player works, what is the biggest bridge, what is the weirdest dinosaur, what is the fastest production car, and so on, including math-based card tricks.
The girls book is mostly about make-up, manicure, ponies (no, really, there are two sections on horses and one on ponies!), and superstition. The book includes a tarot card, and it dwells on astrology, palm reading, and miscellaneous fortune telling.
What is most galling, however, is the review of the girls book on the National Geographic blog for kids. Not only it is a positive review, but it has excerpts such as
“It is also a JUST for girls book because it talks about girl stuff which is really fun. (…) Did you know that if you are dreaming about a door than there are opportunities ahead? (…) Another chapter that stuck out to me was Palmistry. The book told you which line on your hand is your lifeline and what it meant. It said that since my lifeline was long and curved that I will have a long and healthy life!”
This is on the website of the National Geographic, one of the largest non-profit scientific and educational institutions in the world.
p.s. To be fair, the girls book has a section on “overcoming math phobia,” a section describing the difference between astrology and astronomy, and a section on “women in technology,” which includes a reference to Ada Lovelace and from which I learned that actress Hedy Lamarr (whom I knew as the first actress to appear nude in a mainstream movie) co-invented a technique for information transmission wherein the frequency of transmission is continuously varied (requiring more bandwidth but improving throughput).
Exercise for the reader: find what is wrong with the following paragraphs from an article in the New York Times about the high cost of certain cancer drugs.
In the clinical trial that led to approval of the drug, 27 percent of the 109 patients experienced a reduction in tumor size. The reductions lasted a median of 9.4 months.
But considering all the patients in the trial, only 12 percent had a reduction in tumor size that lasted for more than 14 weeks.
Update: from the press release of the pharmaceutical company:
The results of the trial demonstrated that 29 of 109 evaluable patients, or 27%, responded to FOLOTYN. The median duration of response was 287 days, or 9.4 months (range 1-503 days). Thirteen of 109 evaluable patients had a duration of response ≥ 14 weeks (range 98-503 days).
So the median of 29 numbers is 287, and 16 of those numbers are less than 98.
About a week ago, the email server used by climate scientists at the University of East Anglia was hacked, and emails dating as far back as 1996 were posted online.
National Review, the conservative magazine, “asked its environmentalism experts to weigh in” on the implications of the leak. One of the experts is Henry Payne, billed as “an editorial writer and cartoonist with the Detroit News.” According to wikipedia, Mr. Payne is a history major.
As a computer scientist and Chinese food enthusiast, I believe I am more qualified than Mr. Payne to discuss climate change, and I hope National Review will consider asking me to write a piece on the subject next time.
Update: in the next episode of the series everybody is an expert, Sarah Palin writes an op-ed on climate change for the Washington Post. “I’ve always believed that policy should be based on sound science, not politics,” writes Sarah Palin. I am looking forward to zombie Ronald Reagan‘s take on the matter.