Saturday, September 24, 2022

Improving refugee resettlement: insights from market design by Justin Hadad and Alexander Teytelboym

 The Autumn 2022 issue of the Oxford Review of Economic Policy is about forced migration.  Here's a paper directly related to market design.

Improving refugee resettlement: insights from market design by Justin Hadad and Alexander Teytelboym, Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 434–448, https://doi.org/10.1093/oxrep/grac013, 15 September 2022

Abstract: The current refugee resettlement system is inefficient because there are too few resettlement places and because refugees are resettled to locations where they might not thrive. We outline how ideas from market design can lead to better resettlement practices. In particular, we discuss how market design can incentivize participation of countries in resettlement and improve the matching of refugees at international and local levels; some of these insights have already put into practice. Finally, we highlight several further applications of market design in refugee resettlement, including cardinal preference submission and matching with transfers.

"There is an acute shortage of resettlement. Resettlement is a public good from the point of view of countries (i.e. if one country contributes by resettling a refugee, all other countries benefit), so it is not surprising that it is underprovided (Moraga and Rapoport, 2014). The UNHCR predicts that 1.47 million refugees will need resettlement in 2022––the highest ever number (UNHCR, 2021e). Numbers of resettled refugees fluctuate—in part driven by need, and in part driven by the willingness of the largest hosting countries, such as the United States, to resettle (see Figure 1). The refugees in need of resettlement are the most vulnerable kinds of refugees (see Figure 2); they have often suffered persecution and violence above and beyond the terrible experiences of most refugees.

...

"The UNHCR is responsible for sending the applications of refugees to resettling countries. The process works as follows: the UNHCR identifies a refugee family in need of resettlement, and submits an application on their behalf to a country that may resettle them. If the application is accepted, the country becomes responsible for resettling the refugee according to its own rules; if the application is rejected, the UNHCR can submit an application to another country. The process can take months, if not years. Given the shortage of resettlement places, the UNHCR has a strong incentive to maximize the expected number of successful applications rather than to try to find the best matches between refugees and countries. In 2020, the UNHCR submitted the applications of over 39,500 refugees to resettling countries, which led to just 22,800 individuals departing to these countries (UNHCR, 2021d). This suggests that there is potential to improve the allocation of international resettlement submissions."

***********

Here's the rest of the issue:

Forced Migration

CONTENTS

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 403–413, https://doi.org/10.1093/oxrep/grac025

PART 1

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 414–433, https://doi.org/10.1093/oxrep/grac018
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 434–448, https://doi.org/10.1093/oxrep/grac013

PART 2

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 449–486, https://doi.org/10.1093/oxrep/grac012
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 487–513, https://doi.org/10.1093/oxrep/grac022

PART 3

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 514–530, https://doi.org/10.1093/oxrep/grac017
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 531–556, https://doi.org/10.1093/oxrep/grac021
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 557–577, https://doi.org/10.1093/oxrep/grac015
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 578–594, https://doi.org/10.1093/oxrep/grac024

PART 4

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 595–624, https://doi.org/10.1093/oxrep/grac014
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 625–653, https://doi.org/10.1093/oxrep/grac023
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 654–677, https://doi.org/10.1093/oxrep/grac019
Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 678–698, https://doi.org/10.1093/oxrep/grac016

POSTSCRIPT

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Pages 699–716, https://doi.org/10.1093/oxrep/grac020

CORRECTION

Oxford Review of Economic Policy, Volume 38, Issue 3, Autumn 2022, Page 717, https://doi.org/10.1093/oxrep/grac030

Friday, September 23, 2022

Choosing between public and private schools: vouchers in Arizona

There's a fight over public versus private school funding in Arizona. Here's the background:

Arizona OKs Biggest US School Voucher Plan, Faces Challenge. Republican Gov. Doug Ducey has signed a massive expansion of Arizona’s private school voucher system.  AP, July 7, 2022

"Republican Gov. Doug Ducey on Thursday signed a massive expansion of the state’s private school voucher system, even as he faced a promised effort by public school advocates to block the bill and ask voters to erase it during November’s election.

"The expansion Ducey signed will let every parent in Arizona take public money now sent to the K-12 public school system and use it to pay for their children’s private school tuition or other education costs.

...

"Ducey has championed “school choice” during his eight years in office. He signed a universal voucher expansion in 2017 with enrollment caps that was referred to the ballot by a grassroots group called Save Our Schools Arizona.

"Voters soundly rejected the expansion by a 2-to-1 vote in the 2018 election, but advocates of what are formally called “Empowerment Scholarship Accounts” pushed ahead with new expansions anyway. The universal voucher bill passed with only support from majority Republican lawmakers in the legislative session that ended early on June 25."

**********

And Salon brings us up to date:

Arizona's school privatization battle heats up: Will the voters get to decide?  Republicans' massive school voucher plan may yet be defeated (again) — but the challenge is stiffer this time By KATHRYN JOYCE, SEPTEMBER 20

"A fight over the future of the most sweeping school voucher program in the country has heated up in Arizona over the last few weeks, as public school advocates race to gather enough signatures to trigger a ballot referendum aimed at overturning a voucher law recently passed by the state's Republican-dominated legislature. The referendum campaign, which faces a crucial deadline this Friday, has drawn intense opposition from Arizona conservatives. This has included funding for multiple anti-referendum websites, roadside protests starring Republican legislators and, over the last two weeks, conflicts between activists both on social media and in the streets. 

...

"Under the new law, any Arizona parent who opts their children out of public school will receive a debit card with an average balance of just under $7,000, which they can use to spend on almost any educational needs they choose, from private school tuition to homeschooling expenses to buying computers to hiring private teachers for "microschools." Public education advocates immediately warned that such a huge transfer of public funds to private hands could be the death knell for public schools, which would likely have to make untenable cuts to teaching staff and school programs.

...

"From the inception of Arizona's ESAs, critics have charged that they're little more than a workaround to funnel public tax dollars to private schools. The idea was born after a court found in 2009 that two earlier Arizona school voucher programs were unconstitutional, violating the state's prohibition on using public money for private education. In 2011, under the guidance of the Goldwater Institute, a conservative think tank, the state launched an ingenious alternative: sending state funds directly to parents, who spend the money as they see fit. The ESA option then became a nationwide model, copied in numerous other states and increasingly seen by conservative education reform activists as "the purest form of school choice." 


HT: Bertan Turhan


Thursday, September 22, 2022

Market design workshop at Iowa State University

 I'll give a public talk this evening to open a market design workshop tomorrow and Saturday:

Two-day Workshop: September 23-24, 2022, Heady Hall 360A, Iowa State University

Organizers: Ran Shorrer, Bumin Yenmez, Bertan Turhan  

Program: MARKET DESIGN WORKSHOP PROGRAM

Day 1: Friday, September 23, 2022 (Heady Hall 368A)

SESSION 1

8:00-8:40 Rakesh Vohra (w/ Thanh Nguyen)

“(Near) Substitute Preferences and Equilibria with Indivisibilities”

8:40-9:20 Federico Echenique (w/ Sumit Goel and SangMok Lee)

“Stable Allocations in Discrete Economies”

9:20-10:00 Marzena Rostek

“Decentralized-Market Design”

Chair: Tarun Sabarwal

------------------------------------------------------------------------------------------------

BREAK: 10:00-10:30

------------------------------------------------------------------------------------------------

SESSION 2

10:30-11:10 Karam Kang (w/ Giulia Brancaccio)

“Search Frictions and Product Design in the Municipal Bond Market”

11:10-11:50 Mariana Lavarde

“Distance to Schools and Equal Access in School Choice Systems”

11:50-12:30 Atila Abdulkadiroğlu (w/ Aram Grigoryan)

“Priority-based Assignment with Reserves and Quotas”

Chair: David Cooper

------------------------------------------------------------------------------------------------

LUNCH: 12:30-1:40 (Heady 360)

------------------------------------------------------------------------------------------------


SESSION 3

1:40-2:20 Bumin Yenmez (w/ Isa Hafalir and Fuhito Kojima)

“Design on Matroids: Diversity vs Meritocracy”

2:20-3:00 Orhan Aygün (w/ Bertan Turhan)

“Affirmative Action in India: Restricted Strategy Space, Complex Constraints, and

Direct Mechanism Design”

3:00-3:40 Nick Arnosti

“Explainable Affirmative Action”

Chair: Atila Abdulkadiroğlu

------------------------------------------------------------------------------------------------

BREAK: 3:40-4:10

------------------------------------------------------------------------------------------------


SESSION 4

4:10-4:50 Eric Budish

“The Economic Limits of Bitcoin and Anonymous, Decentralized Trust on the Blockchain”

4:50-5:30 Eduardo Azevedo (w/ David Mao, Jose Montiel Olea, and Amilcar Velez)

“A/B Testing with Gaussian Priors”

5:30-6:10 Ran Shorrer (w/ Yannai Gonczarowski and Scott Kominers)

“To Infinity and Beyond: Scaling Economic Theories via Logical Compactness”

Chair: Al Roth

---------------------------------------------------------------------------------- 


Day 2: Saturday, September 24, 2022

SESSION 5

8:00-8:40 Thayer Morrill (w/ Peter Troyan)

“Desirable Rankings: A New Method for Ranking Outcomes of a Competitive Process”

8:40-9:20 Lars Ehlers (w/ Christian Basteck)

“Strategy Proof and Envy-Free Random Assignment”

9:20-10:00 Itai Ashlagi (w/ Jacob Leshno, Pengyu Qian, and Amin Saberi)

“Price Discovery in Waiting Lists: A Connection to Stochastic Gradient Descent”

Chair: Rakesh Vohra


------------------------------------------------------------------------------------------------

BREAK: 10:00-10:30

------------------------------------------------------------------------------------------------

SESSION 6

10:30-11:10 Josue Ortega (w/ Thilo Klein)

“Improving Efficiency and Equality in School Choice”

11:10-11:50 Aram Grigoryan

“Transparency in Allocation Problems”

11:50-12:30 Inácio Bó (w/ Rustam Hakimov)

“Pick-an-Object Mechanisms”

Chair: Federico Echenique

Wednesday, September 21, 2022

Economists as Engineers: Public lecture at Iowa State University tomorrow

 
I'll be travelling today to Ames Iowa, to give a public lecture tomorrow evening at Iowa State University (and to attend a market design conference there on Friday and Saturday)



"This event will be recorded and available for two weeks on the Lectures website at 
https://www.lectures.iastate.edu/recordings/available-recordings "

Tuesday, September 20, 2022

Investment Incentives in Truthful Approximation Mechanisms by Akbarpour, Kominers, Li, Li and Milgrom

Computationally intractable optimization problems often allow approximate solutions that are 'close enough' to the optimal solution.  But these approximation algorithms can radically change the incentives to the participants, or not.  Here's a paper on frontier of market design and computer science, from the KIT — Paris — ZEW Workshop on Market Design from June 2022.

Investment Incentives in Truthful Approximation Mechanisms, by Mohammad Akbarpour, Scott Duke Kominers, Kevin Michael Li, Shengwu Li, and Paul Milgrom.   May 16, 2022

"Abstract: We study investment incentives in truthful mechanisms that allocate resources using approximation algorithms instead of exact optimization. In such mechanisms, the price a bidder pays to acquire resources is generally not equal to the change in other bidders’ welfare—and these externalities skew investment incentives. Some allocation algorithms are arbitrarily close to efficient, but create such perverse investment incentives that their worst-case welfare guarantees fall to zero when bidders can invest before participating in the mechanism. We show that an algorithm’s guarantees in the allocation and investment problems coincide if and only if that algorithm’s “confirming” negative externalities are sufficiently small. Algorithms that exclude confirming negative externalities entirely (XCONE algorithms) thus have the same worst-case performance for the allocation and investment problems."

 

A "confirming" negative externality is an investment that doesn't change the investor's allocation but imposes a negative externality on the market.

Monday, September 19, 2022

Crowdsourcing organ transplant ethics

 In Slate, an upbeat article about the ethical issues associated with deceased organ allocation and (before that) access to dialysis, and the benefits and difficulties with crowdsourcing the solutions.  

The Kidney Transplant Algorithm’s Surprising Lessons for Ethical A.I.  A more democratic approach to A.I. is messy, but it can work.  BY DAVID G. ROBINSON

This article is adapted from Voices in the Code: A Story About People, Their Values, and the Algorithm They Made, out Sept. 8 from Russell Sage Foundation Press.

" in the world of organ transplants, surgeons and data scientists have an unusual habit of being brutally honest about the human lives behind their work—of inviting others into the impossible choices their field confronts. For better and worse, the organ transplant system is itself a real-life laboratory of more inclusive, accountable techniques for building and using A.I.—approaches that are now being proposed in U.S. and EU legislation that could cover courtrooms, hiring, housing, and many other sensitive domains.

...

"Where did this culture of moral humility—one that’s now shaping the design of a high-stakes A.I. system—come from?

"Collaborative decision-making about hard ethical choices in kidney medicine began before the digital revolution. It began before there were many kidney transplants. "

After the development of dialysis there were..."just a handful of dialysis machines, ...Whom to save? Scribner and his team were inundated with pleas from dying patients and their doctors.

"Faced with this quandary, Scribner and his colleagues chose to do something extraordinary: They shared their moral burden with the Seattle community they served. Rather than pretending that their technical expertise gave them special moral standing, they chose to be morally modest, and to widen the circle. The doctors still decided who was medically eligible for dialysis. But then, they established a second committee, a group of seven laypeople chosen by the local medical society, who would make the non-medical decision of how to allocate the few available slots among the many eligible patients. The committee members were given some basic education about kidney medicine, but weren’t told how to make their moral choices.

They Decide Who Lives, Who Dies” was the headline of a 1962 Life magazine article about this new group. Its members, who were anonymous, were photographed in shadow. A clerical collar can be seen on one. The lone woman of the group, a homemaker, clasps a pair of reading glasses in her folded hands. The article reported that the committee’s approach was based on “acceptance of the principle that all segments of society, not just the medical fraternity, should share the burden of choice as to which patients to treat and which ones to let die.”

"The Life story described some biases that played out on the committee—they favored male breadwinners who had children to support—and it triggered widespread revulsion. A pair of scholars wrote that the committee was judging people “in accordance with its own middle-class suburban value system: scouts, Sunday school, Red Cross. This rules out creative nonconformists … the Pacific Northwest is no place for a Henry David Thoreau with bad kidneys.” The original Life story never mentioned race, but later reporting suggested the committee had been biased in favor of white applicants. The committee only ran for a few years. Other dialysis facilities used different rationing strategies—including first-come, first-served—and in 1972 Congress passed an extraordinary law to provide dialysis at public expense through Medicare to all patients who needed it. That proved to be a humane, if extremely costly, escape route from the rationing problem that Scribner once faced.

"Along with all its faults, I think the Seattle committee also gave us much to admire. It was profoundly, even uncomfortably, honest about the hard choices at the center of kidney medicine. It refused to pretend that such choices were—or ever could be—entirely technical. And it tried, albeit clumsily, to democratize the values inside a complex, high-tech system. The Seattle physicians and their lay colleagues were rationing a scarce supply of dialysis treatments. But even after Congress provided dialysis for everyone, the shortage of transplantable kidneys was destined to spark similar questions, ones we still face today."


HT: Tom Riley

Sunday, September 18, 2022

Canadian Blood Services to start paying Canadian plasma donors

 CBC news has the story, which seems to mark a turning point in a long struggle with repugnance for paying donors.

Canadian Blood Services signs agreement with private company to boost national plasma supply.  Some advocates calling for the resignation of Canadian Blood Services leaders over agreement. by Stephanie Dubois 

"Canadian Blood Services (CBS) is partnering with a private healthcare company to boost Canada's national blood plasma supply, the organization announced Wednesday.

...

"CBS has signed an agreement with Grifols, a company headquartered in Spain, which specializes in producing plasma medicines, the national blood collection organization said in a news release.

...

"Grifols will help CBS meet national targets for plasma supply by both collecting paid-for plasma and by turning Canadian plasma into immunoglobulins —a form of specialized medications called plasma protein products– for Canadian patients. 

...

"Health Canada says on its website there's currently "not enough plasma collected in Canada to meet the demand," and most of the plasma products distributed by CBS and Héma-Quebec are purchased from U.S. manufacturers and made from U.S. paid-donor plasma. "

Saturday, September 17, 2022

Non-directed organ donors and NLDAC financial support

For some years I've been a member of the advisory group of the National Living Donor Assistance Center (NLDAC) which is authorized to offer federally funded financial support (for travel, and now also for lost wages and childcare expenses) to needy donors whose recipients also cannot afford to offer such support. As kidney exchange has grown, so have the number of non-directed donors, who don't have a particular recipient in mind. In a recent email, NLDAC has defined how these donors can qualify for financial assistance.

"Defining Non-Directed Donors

"Eligibility for NLDAC depends primarily on the recipient's household income. This is because the Organ Donation and Recovery Improvement Act requires NLDAC to assess the recipient's ability to reimburse their donor before providing reimbursement with federal funding. Most donors have a particular recipient in mind, and that person is allowed to reimburse their expenses, if they are willing and able to do so. NLDAC provides reimbursement when the recipient cannot afford to provide it. Some donors do not have a recipient to ask for help, though. A non-directed donor is a living donor with no intended recipient. These donors can apply to NLDAC without recipient information because there is no identified recipient. Non-directed donors are eligible for NLDAC regardless of their eventual recipient's information, as long as the donor meets the residency requirements and applies on time. 

"Let's consider some examples:

"Tina heard on the news that there are 5,000 people waiting for a kidney transplant in her state. She called a transplant center and asked that they give her kidney to anyone who needs it, if she is approved to donate. Tina is a non-directed donor because she has no intended recipient. 

"Anthony read about a stranger's search for a living kidney donor on Facebook. Though he doesn't know the person, he would like to be evaluated as a potential donor for them. He is a directed donor because he has an intended recipient, even though he doesn't know them personally. 

"Jacqueline wants to donate to a member of her church without revealing her identity to the recipient. She is a directed donor because she has an intended recipient, though she wants to remain anonymous. 

"Esther wanted to donate to her husband, but they are not a good match. Through kidney paired donation, she donates to a stranger, and the stranger's loved one donates to her husband. Because Esther has an intended recipient who received a transplant through her donation, she is a directed donor. 

"Devin was being evaluated as a potential living donor to his uncle when his uncle received a deceased donor transplant. Devin decided he was still willing to donate even though his uncle no longer needed his organ, and asked the transplant center to give his kidney to anyone on the waitlist. Devin is now a non-directed donor because he does not have an intended recipient anymore. 

"Which of these donors can apply to NLDAC without their recipient's information? Tina and Devin, because they are donating without an intended recipient. Anthony, Jacqueline, and Esther can apply with their intended recipient, and NLDAC will keep the donor and recipient's information private. Esther would apply with her originally intended but incompatible recipient, her husband."

************

All my posts on NLDAC:  https://marketdesigner.blogspot.com/search?q=nldac&max-results=20&by-date=true


Friday, September 16, 2022

A milestone and a stepping stone: 1 million U.S. organ transplants

 Here's the story from the AP, about the 1,000,000th transplant in the U.S., a milestone reached last Friday:

US counts millionth organ transplant while pushing for more By LAURAN NEERGAARD September 9, 2022

"The U.S. counted its millionth organ transplant on Friday, a milestone that comes at a critical time for Americans still desperately waiting for that chance at survival.

"It took decades from the first success — a kidney in 1954 — to transplant 1 million organs

...

"Yet the nation’s transplant system is at a crossroads. More people than ever are getting new organs — a record 41,356 last year alone. At the same time, critics blast the system for policies and outright mistakes that waste organs and cost lives.

"The anger boiled over last month in a Senate committee hearing where lawmakers blamed the United Network for Organ Sharing, a nonprofit that holds a government contract to run the transplant system, for cumbersome organ-tracking and poor oversight."

Thursday, September 15, 2022

Depreciated currency

I'm flying home today from Argentina, where I took part in the TTS2022 international transplant conference.   I had to change dollars to pesos, which is made more complicated by the fact that Argentina has experienced persistently very high inflation.  But I feel on much more solid ground than if I had been in Venezuela, where inflation has wreaked havoc.

 David Klinowski recently finished a postdoc at Stanford and moved to Pitt. As a souvenir, he gave us this peacock, made by an artist from depreciated Venezuelan currency, which happens to have pictures of birds.  Persistent inflation has made this one of the high value uses of these old bills.
















Here's a snippet of inflation data from the IMF: 

Venezuela: Inflation rate from 2012 to 2022 (compared to the previous year)


********

In contrast to Venezuela, inflation in Argentina could be worse--it's less than 100% a year--double digits rather than 5 digits--although it's still among the highest in the world:

Argentina: Inflation rate from 2004 to 2027(compared to the previous year), with 2014-16 missing (and estimated going forward)



Wednesday, September 14, 2022

TTS2022 Awards--Congratulations

 Today at TTS2022, prizes will be awarded.  One that I know is very well deserved, is to Dr. Vivek Kute, for his extraordinary achievements in kidney transplantation in India. Congratulations to all the prize winners.


I've followed Dr. Kute's work over the years in multiple posts.

Tuesday, September 13, 2022

The First 52 Global Kidney Exchange Transplants: today at TTS2022 in Buenos Aires

 Tomorrow at TTS2022 in Buenos Aires, Mike Rees will present

The First 52 Global Kidney Exchange Transplants: overcoming multiple barriers to transplantation by MA Rees, AE Roth , IR Marino, K Krawiec, A Agnihotri, S Rees, K Sweeney, S Paloyo, T Dunn, M Zimmerman, J Punch, R Sung, J Leventhal, A Alobaidli, F Aziz, E Mor, T Ashkenazi, I Ashlagi, M Ellis, A Rege, V Whittaker, R Forbes, C Marsh, C Kuhr, J Rogers, M Tan, L Basagoitia, R Correa-Rotter, S Anwar, F Citterio, J Romagnoli, and O Ekwenna.  

Introduction: Many barriers currently stand in the way of achieving international kidney exchange including: financial, regulatory, logistical, cultural, immunological and legal barriers. 

Methods: The Alliance for Paired Kidney Donation serves patients in 15 countries. Ten of these countries have participated in Global Kidney Exchange (GKE) transplants in which either living donors, their kidneys or recipients have traveled internationally to achieve successful living donor kidney transplantation (LDKT). In all cases, barriers were present that prevented LKDT in the donor or recipient country of origin.

Results: Between January of 2015 and February of 2022, GKE has produced 11 chains and 4 cycles that has provided LDKT for 17 international patients from 10 countries to be transplanted, as well as 35 LDKT for patients in the United States (US). GKE chains lengths have ranged from 1 to 11; cycles were length 2 or 3. Eight GKE transplants overcame immunologic barriers, 4 financial barriers, and 5 both immunologic and financial barriers. GKE has involved 19 US transplant centers across 18 states and 38% of recipients were minorities. For US recipients 11% had blood type (BT)-A, 57% BT-0, 17% BT-B, and 14% BT-AB; for international recipients 41% had BT-A, 53% BT-O and 6% BT-B. The PRA was 0-20% for 23 patients, 21-79% for 14 and > 80% for 15 (10 international). International pairs were funded by a combination of self-pay, insurance and philanthropy. Transplanting 35 US patients saved US healthcare payers $7-10M vs. dialysis. International recipients have 100% 3-year patient and graft survival and all international donors are alive and have normal creatinine and blood pressure.

Conclusion: GKE overcomes financial and immunological barriers to transplantation. Savings from avoided dialysis offers scalability. Our program ensures transparency of international pair selection, emphasis on donor safety, and assurance of longterm immunosuppression for recipients as prerequisites for sustainability.