Our multi-disciplinary team is dedicated to using the the power of data for social innovation. One of the biggest challenges facing charities and non-profits is the lack of data related resources at their disposal. By providing civic analytics to the social sector, we aspire to create tangible, real-world impact while providing data-driven thought leadership on the issues. 

The Team


Stefan Heeke, Executive Director

Stefan believes that data well applied has transformational power in any environment. He studied Economics in Germany and holds a Business Masters Degree from the French ESCP-Europe. Stefan worked in international communication agencies and Digital Marketing before joining SumAll.


Deniz Zorlu, Data Scientist

Deniz is our Data Scientist in residence.  After spending his first career years working in finance, Deniz transitioned to a Data Science role that enabled him to deal with social problems. He is also currently teaching a Data Science course at General Assembly. 


Katie Lee, Project Manager

Prior to SumAll, Katie worked as a consultant for two leading global marketing analytics companies based out of Dublin, Ireland and New York City, with clients in the U.S., Europe and Asia.  She enjoys helping people become more data literate and to understand how it can impact their everyday life in a positive way.  You can also find her on the soccer field and hockey rink.

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Chi Nga Pinky Chan, Social Media and Community Management Intern

Pinky has a BS in Health Science with a concentration in Public Health from Stony Brook University.  During her time there, she has led numerous campus-wide outreach events to raise awareness of health issues and human trafficking.  Today, Pinky continues to take joy in fundraising and advocating for social causes through the use of social media.

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Mary Sitzenstatter, Development and Communications Manager

Mary brings to the SumAll experience in international development, social services, non-profit fundraising, and digital marketing. She spent two years as a Teacher Trainer in the Islamic Republic of Mauritania with the Peace Corps, and she holds an MSW from Hunter College. If Mary isn't busy writing for SumAll or her other employer (and SumAll partner), Power Poetry, she's most likely riding her bike. 


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Adeen Flinker

Adeen is a research scientist specializing in data analysis and signal processing. Formally a neuroscientist pursuing academic research, he received his undergraduate degree in Computer Science from Technion and PhD in Neuroscience from UC Berkeley.  Currently, Adeen is conducting postdoctoral research at NYU.

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Rolando Berrios

Rolando started out as a developer/systems engineer at SenseNet and have worked at the systems group at the NY Times Online, the systems group at Forbes.com, head of systems at Squarespace, and systems architect at Vidavee.  He's dabbled in martial arts, scuba diving and skydiving.  He's also a big fan of any games.

Board Of Directors

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Korey Lee

Korey has led analytics and BI teams at AppNexus and Squarespace defining revenue and product strategy and spent a number of years at Google running business intelligence for AdWords North America and operations for AdSense.  He enjoys numbers, nerds, photography, climbing large mountains and traveling