Mike Luca on social media bans

 Mike Luca writes, in Wired, about social media bans as part of their design.

Social Media Bans Are Really, Actually, Shockingly Common--Booting Trump didn’t set a precedent. From Yelp to Uber to Airbnb, platforms regularly ban users and content, but too often behind the scenes.

"DONALD TRUMP’S ACCOUNTS have been banned on Twitter, Facebook, and a host of other platforms. Every last one of @realdonaldtrump’s 47,000 tweets vanished from the site in an instant, from the birther lies and election conspiracy theories to the 2016 taco bowl tweet. In an explanatory blog post, the company cited the attack on the Capitol and “the risk of further incitement of violence” that might occur by permitting further Trump tweets. His multiplatform removal has drawn cheers from many, as well as the ire of more than a few Trump supporters. The bans have also raised concerns that the companies had gone too far in exercising their power to shape what users see.

...

"To combat review fraud, Yelp and other platforms flag reviews they deem spammy or objectionable and remove them from the main listings of the page. Yelp puts these into a section labeled “not currently recommended,” where they are not factored into the ratings you see on a business’s page. The goal of approaches like this is to make sure people can trust the content they do see.

...

"Ultimately, removing content can be valuable for users. People need to feel safe in order to participate in markets. And, it can be hard to trust review websites riddled with fake reviews, housing rental websites rife with racial discrimination, and social media platforms that are megaphones of misinformation. Removing bad content can create healthier platforms in the long run. There is a moral case for banning the president. There is also a business case."

Tuskegee and transplantation

Here's a complex story from the Chicago Tribune, that conveys just some of the complicated ways that many African Americans relate to transplantation:

Chicago has one female, African-American organ transplant surgeon. She fights disease — and distrust of doctors

“I’ve had patients tell me that they know transplant is experimental,” Simpson said. “I’ve had patients tell me they know white people get preference when it comes to time on the waiting list.”

"(Neither is true.)

“Patients are very frank with me in telling me they know things are unfair or experimental, and they’re the hardest to convince otherwise,” Simpson said. “Those are some of the most heartbreaking cases for me.”

"In some families, a deeply ingrained sense of betrayal, passed down through generations, can permeate doctor visits. It’s a product of medical experiments widely performed on slaves in the mid-1800s, a product of the 40-year Tuskegee syphilis experiment, begun in 1932, that denied hundreds of black men a proper diagnosis or treatment for a debilitating disease, a product of quality medical care existing just out of geographic reach."
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This remindes me of two related papers on the Tuskegee effect on black patients' relationships to American medicine, coauthored by my remarkable colleague Marcella Alsan:

Tuskegee and the Health of Black Men

Marcella Alsan and Marianne Wanamaker

The Quarterly Journal of Economics, Volume 133, Issue 1, 1 February 2018, Pages 407–455,https://doi.org/10.1093/qje/qjx029

Abstract

For 40 years, the Tuskegee Study of Untreated Syphilis in the Negro Male passively monitored hundreds of adult black men with syphilis despite the availability of effective treatment. The study’s methods have become synonymous with exploitation and mistreatment by the medical profession. To identify the study’s effects on the behavior and health of older black men, we use an interacted difference-in-difference-in-differences model, comparing older black men to other demographic groups, before and after the Tuskegee revelation, in varying proximity to the study’s victims. We find that the disclosure of the study in 1972 is correlated with increases in medical mistrust and mortality and decreases in both outpatient and inpatient physician interactions for older black men. Our estimates imply life expectancy at age 45 for black men fell by up to 1.5 years in response to the disclosure, accounting for approximately 35% of the 1980 life expectancy gap between black and white men and 25% of the gap between black men and women. 

and (from a previous post)

Saturday, August 18, 2018

Diversity isn't just about role models: Alsan, Garrick and Graziani on black male doctors and patients

Medical compliance--following the doctor's "orders,"--is a big issue in medical care, and here's an article that reports a novel field experiment suggesting that black male doctors treating black men may have more success than non-black docs.

Does Diversity Matter for Health? Experimental Evidence from Oakland
Marcella Alsan, Owen Garrick, Grant C. Graziani
NBER Working Paper No. 24787

"We study the effect of diversity in the physician workforce on the demand for preventive care among African-American men. Black men have the lowest life expectancy of any major demographic group in the U.S., and much of the disadvantage is due to chronic diseases which are amenable to primary and secondary prevention. In a field experiment in Oakland, California, we randomize black men to black or non-black male medical doctors and to incentives for one of the five offered preventives — the flu vaccine. We use a two-stage design, measuring decisions about cardiovascular screening and the flu vaccine before (ex ante) and after (ex post) meeting their assigned doctor. Black men select a similar number of preventives in the ex-ante stage, but are much more likely to select every preventive service, particularly invasive services, once meeting with a doctor who is the same race. The effects are most pronounced for men who mistrust the medical system and for those who experienced greater hassle costs associated with their visit. Subjects are more likely to talk with a black doctor about their health problems and black doctors are more likely to write additional notes about the subjects. The results are most consistent with better patient-doctor communication during the encounter rather than differential quality of doctors or discrimination.Our findings suggest black doctors could help reduce cardiovascular mortality by 16 deaths per 100,000 per year — leading to a 19% reduction in the black-white male gap in cardiovascular mortality.
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And here's a related very recent obituary:
Bill Jenkins, Who Tried to Halt Tuskegee Syphilis Study, Dies at 73

"Bill Jenkins, a government epidemiologist who tried to expose the unethical Tuskegee syphilis study in the 1960s and devoted the rest of his career to fighting racism in health care, died on Feb. 17 in Charleston, S.C. He was 73."

Reputation in online marketplaces

Two recent NBER papers tell us about trust, quality, and reputation in online marketplaces.

BUYING REPUTATION AS A SIGNAL OF QUALITY:
EVIDENCE FROM AN ONLINE MARKETPLACE
Lingfang (Ivy) Li, Steven Tadelis, Xiaolan Zhou
Working Paper 22584, http://www.nber.org/papers/w22584

ABSTRACT: Reputation is critical to foster trust in online marketplaces, yet leaving feedback is a public good that can be under-provided unless buyers are rewarded for it. Signaling theory implies that only high quality sellers would reward buyers for truthful feedback. We explore this scope for signaling using Taobao's "reward-for-feedback" mechanism and find that items with rewards
generate sales that are nearly 30% higher and are sold by higher quality sellers. The market design implication is that marketplaces can benefit from allowing sellers to use rewards to build reputations and signal their high quality in the process.

**********

DESIGNING ONLINE MARKETPLACES:

TRUST AND REPUTATION MECHANISMS

Michael Luca

Working Paper 22616, http://www.nber.org/papers/w22616

ABSTRACT: Online marketplaces have proliferated over the past decade, creating new markets where none existed. By reducing transaction costs, online marketplaces facilitate transactions that otherwise would not have occurred and enable easier entry of small sellers. One central challenge faced by designers of online marketplaces is how to build enough trust to facilitate transactions between strangers. This paper provides an economist’s toolkit for designing online marketplaces, focusing on trust and reputation mechanisms.

Trust and crime: Reputation in the (illegal) market for sex

Quartz has an article on how sex workers can vet new customers, in the age of the internet: Sex workers have created the perfect method for keeping people honest online. (I like the url better than the headline: http://qz.com/621994/trust-and-crime/

"If you work at Goldman Sachs in New York City and you want to tie up a woman and then have sex with her, there’s a good chance you’ll first have to speak to Rita.
She’ll insist on calling your office, speaking to the switchboard operator, and being patched through to your desk. Then she will want to check out your profile on the company website and LinkedIn. She’ll demand you send her message from your work email, and require a scan of either your passport or driver’s license.
...
"Mid-range prostitution is a relatively new market, enabled by technology. Before the internet, it was hard for escorts to find customers: They had to either walk the streets searching for customers (the lower end of the market), rely on word-of-mouth, or work with agencies. Walking the streets was dangerous, while agencies ate up a large share of workers’ profit and autonomy, and created a bottleneck to entering the market. The internet changed all that.

“Before the internet, agencies provided the steady flow of clients and screening, but their capacity was capped,” Baylor University economist Scott Cunningham said. Soon after Craigslist launched in 1995, US escorts quickly started marketing directly to customers online. This newfound ability to advertise on the internet grew the market, said Cunningham, because more women and men could work independently
...
"Even criminals need someone they can trust

"If you’re selling something illegal, you can’t rely on the law to make sure the buyer upholds their end of the deal. Once the bill comes, clients might turn violent, or turn out to be cops. That means trust commands a large premium and that’s the centerpiece of Rita’s business model: watertight background checks on would-be johns.

"Rita represents sex workers who offer BDSM in addition to sex. When rough play is on the list of services you offer, a high level of trust is essential; hence, Rita’s elaborate screening process, which can take days. “I am looking to weed out police and crazies,” she said. She estimates that only one in four potential customers ultimately passes. Those who do win some time with a professional escort/dominatrix, but it comes at a hefty price: Each hour can cost up to $800, and Rita’s cut is 30%."

Instructions are part of a market's design

Whenever my colleagues and I help design a new marketplace, we're very aware that a part of the market mechanism are the instructions that accompany it. There's no reason to assume that the benefits of a strategy-proof mechanism, for example, will be realized if the participants aren't made fully aware that it is strategy-proof, so that it is safe for them to reveal their true preferences.

That is why I was glad when the HBS MBA program invited me to explain the modified serial dictatorship mechanism that Clayton Featherstone and I designed for the first year of operation of a 2nd year MBA field experience module, in which Harvard MBA students will choose countries in which to spend time at a company.  (We felt it was particularly important to start with a strategy-proof mechanism, for reasons we hope to write about in the not too distant future.)  Here's the video of my explanation (which can also be found at http://video.hbs.edu/videotools/play?clip=aroth_field2_algorithm or, if that is gated, http://stream.hbs.edu/remediated/cd/aroth_field2_algorithm.mp4)

While I think of it, let me mention that Clayton is an unusually talented and versatile market designer, theorist and experimenter who will be on the econ job market this year.

"Girl taxi" and "Ladies Nights"

The WSJ reports 'Girl Taxi' Service Offers Haven to Beirut's Women .

"...these days the city's transport staple is facing some serious competition from a growing army of female taxi drivers, dressed in stiff-collared white shirts, dark shades, pink ties and small pink flowers tucked into their flawlessly coiffed hair.
All of them drive for Banet Taxi, or "girl taxi" in Arabic. It is Lebanon's first cab service for women, by women. You can't miss the company's signature candy-pink cars."
...
"The company is part of a regional trend. Entrepreneurs across the Middle East have recognized the business potential in offering secure transportation options for women. Banet Taxi follows on the heels of successful women-only transportation models in Dubai, Tehran and Cairo."

..."It is the promise of a safe and uneventful ride that attracts a wide range of female passengers: older women who want a quiet drive, young women out partying until late at night, and even preschoolers put in the cars by their teachers.
Passengers' reasons for choosing Banet are based, in part, on their cultural and religious backgrounds. Beirut's population breaks down roughly into thirds, Christian, Sunni and Shiite. Conservative Muslim women might take Banet Taxi to accommodate rules against traveling with unknown men. Others just want to put comfort and safety first."

While single sex markets thrive in some venues, others use gender as a basis for discriminatory pricing, with different prices for men and women. Economists mostly don't find this malign in two-sided platforms like those that provide dating opportunities, since they need to attract both genders in comparable proportions. So, for example, some clubs have 'ladies nights,' in which women are admitted for free or at a lower cover charge.

One lawyer is very annoyed by this: N.Y. Lawsuit Calls 'Ladies' Night' Discriminatory . However Roy Den Hollander "ANTI-FEMINIST LAWYER"--N.Y. Times seems to be mostly losing these cases, and has drawn this unsympathetic portrait from the New Yorker: Hey, La-a-a-dies!

Trust and trustworthiness: promoting and maintaining it

Trust is essential for all sorts of transactions, and how to set up institutions to promote trust and trustworthiness in the marketplace is a big concern of market design.

It is even a big concern of armies trying to win the hearts and minds of a population in the face of a guerrilla insurgency. There's a very interesting essay in the Washington Post about earning, maintaining and restoring trust, by Admiral Mike Mullen, the Chairman of the Joint Chiefs of Staff: Building Our Best Weapon.

On a more technical note, I'm reading Community Structure and Market Outcomes: Towards a Theory of Repeated Games in Networks by Itay Fainmesser (who you can try to hire next year). He is interested how patterns of connections between buyers and sellers can promote trustworthy behavior through repeated play, and how the effort to achieve trust in the marketplace by engaging in long term relationships may exclude some parties from the market. In this connection he writes "...repeated interactions cannot perfectly substitute for institutions..."

The kinds of institutions he is thinking of are both legal (if you can sue me for non-performance, this makes it easier to trust me), and reputational (if you can give me a credible negative review that will impede my ability to transact in the future, this also makes it easier to trust me).

As it happens, I've also been reading about the recent redesign of eBay's reputational system: "ENGINEERING TRUST - RECIPROCITY IN THE PRODUCTION OF REPUTATION INFORMATION," - by Gary Bolton, Ben Greiner, and Axel Ockenfels. It is a very nice market design paper.

They describe some of the design concerns behind eBay's 2007 rollout of its new, more detailed feedback system, in which buyers are able to give some feedback on sellers anonymously. In particular, they describe how they and eBay became concerned that the old reputation system became less informative than it might have been, because the pattern of reciprocally positive feedback concealed underlying dissatisfactions. They describe how (both prospectively and retrospectively) they compared the relevant field data, and how laboratory experiments helped verify the intuitions gained in that way, and allowed them to see the efficiency effects of an improved reputation system.