Redesigning VolunteerMatch's Ranking Algorithm: Toward More Equitable Access to Volunteers

54 Pages Posted: 5 Jul 2023

See all articles by Vahideh Manshadi

Vahideh Manshadi

Yale School of Management

Scott Rodilitz

University of California, Los Angeles (UCLA) - Anderson School of Management

Daniela Saban

Stanford Graduate School of Business

Akshaya Suresh

Yale School of Management

Date Written: July 2, 2023

Abstract

In collaboration with VolunteerMatch (VM)---the world's largest online platform for connecting volunteers with nonprofits---we designed and implemented a new display ranking algorithm. VM's original ranking algorithm was intended to maximize efficiency (i.e., the total number of connections), but as a consequence it repeatedly displayed the same few opportunities at the top of its ranking, effectively limiting access to volunteers for the other opportunities. To incorporate VM's desire for equity (defined as the weekly number of opportunities with at least one connection) along with efficiency, we propose a modeling framework for online display ranking in settings where it is important to manage the trade-off between the total number of connections and the equitable allocation of these connections. Taking an adversarial approach in evaluating the performance of online algorithms, we show that a simple class of algorithms that applies a penalty to opportunities after each connection provides a strong (and, in certain regimes, optimal) performance guarantee. Based on our theoretical development, we propose SmartSort, a simple online display ranking algorithm with a penalty term that we calibrated using VM's data and simulation. We implemented SmartSort in two experiments, covering Dallas-Fort Worth and all of Southern California. Using a difference-in-differences analysis, we find that the implementation of SmartSort led to a 8-9% increase in the weekly average number of opportunities with at least one connection (consistent across both experiments) without any meaningful decrease in the total number of connections, implying a Pareto improvement for VM. Based on the success of our experiments, SmartSort has now been deployed nationwide. If SmartSort has a similar distributional effect on a national scale, every year, an additional 30,000 connections will go to opportunities that would have otherwise lacked access to volunteers.

Keywords: volunteering, equitable allocation, nonprofit operations, online experiments, online platforms

Suggested Citation

Manshadi, Vahideh and Rodilitz, Scott and Saban, Daniela and Suresh, Akshaya, Redesigning VolunteerMatch's Ranking Algorithm: Toward More Equitable Access to Volunteers (July 2, 2023). Available at SSRN: https://ssrn.com/abstract=4497747 or http://dx.doi.org/10.2139/ssrn.4497747

Vahideh Manshadi

Yale School of Management ( email )

135 Prospect Street
P.O. Box 208200
New Haven, CT 06520-8200
United States

Scott Rodilitz

University of California, Los Angeles (UCLA) - Anderson School of Management ( email )

110 Westwood Plaza
Los Angeles, CA 90095-1481
United States

Daniela Saban

Stanford Graduate School of Business ( email )

655 Knight Way
Stanford, CA 94305-5015
United States

Akshaya Suresh (Contact Author)

Yale School of Management ( email )

165 Whitney Ave
New Haven, CT 06511

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