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OCE–Immediate Office 
Room 112-A, Whitten Federal Building (mail stop: 3810)
202-720-4164 (Main Line)
202-720-5955 (Main Line)

Shirley E. Brown
Administrative Officer

Shirley E. Brown is a distinguished Administrative Officer with over 37 years of experience with the Federal Government, including 24 years of specialized expertise with the Department of Agriculture (USDA), Office of the Chief Economist (OCE) systems, procedures, and policies. Highly organized, excellent communicator that is driven by results, with a dedicated focus on USDA’s mission and vision. Prior to joining OCE Ms. Brown worked at the USDA, Economic Research Service for 14 years. Ms. Brown has received several diplomas and certificates in the area of Business Administration.


Shawn Arita
Senior Economist

Shawn Arita serves as a Senior Economist in the Office of the Chief Economist at the U.S. Department of Agriculture, Washington DC. In his role he conducts economic analysis and advises the Chief Economist and senior officials regarding the economic effects of various trade policy issues, ongoing events in global commodity markets, and other areas affecting the U.S. farm economy. He performs economic modelling on policy issues of interest for U.S. agriculture and has conducted model-based assessments as needed by USDA programs such as the MFP and CFAP programs as well as arbitration of WTO trade dispute cases. He has published economic research articles in academic journals such as the American Journal of Agricultural Economics, Food Policy, Ecological Economics, Applied Economic Perspectives and Policy, and others. Prior to this position, Shawn was an economist at the Economic Research Service, USDA and also served at the United States Trade Representative (USTR). Shawn received his Ph.D. from the University of Hawaii and originally hails from the Aloha State.

Vincent Breneman
Senior Geographer

Vince Breneman serves as the Senior Geographer in the Office of the Chief Economist (OCE) at the U.S. Department of Agriculture (USDA). He is responsible for geospatial analytics, data development, and data visualization across a range of agricultural and food sector issues with special focus on agricultural programs, markets and natural disasters. Vince joined the OCE in August of 2019. Prior to that, he served as the Chief of the Research Support Branch and Geospatial Program Manager at the Economic Research Service. Vince has MS and BA degrees in Geography from George Mason University and Virginia Tech.

Jean Buzby
Food Loss & Waste Liaison (Detailee)

Dr. Jean Buzby has worked at the U.S. Department of Agriculture for over 25 years and is currently the USDA Food Loss and Waste Liaison in the Office of the Chief Economist. Prior to this position, she was on detail at the U.S. Environmental Protection Agency’s Resource Conservation and Sustainability Division as a Senior Policy Analyst. For most of her career, she has worked at USDA’s Economic Research Service (USDA/ERS), first as an Agricultural Economist and then as the Chief of the Diet, Safety, and Health Economics Branch in the Food Economics Division. Prior to moving into management, her primary areas of work were food safety, food consumption, and food loss research. Dr. Buzby's food safety research included estimating the costs of foodborne illness, analyzing the legal incentives for firms to produce safer food, and exploring international trade and food safety issues. Her food consumption research was primarily centered on using information gleaned from the Food Availability (Per Capita) Data System. Dr. Buzby is domestically and internationally known for her estimates of food loss at the retail and consumer levels in the United States. Dr. Buzby received her Ph.D. and M.S. in Agricultural Economics from the University of Kentucky.

Senior Economist

Callie McAdams
Senior Economist

Callie McAdams is a Senior Economist for the Office of the Chief Economist at the U.S. Department of Agriculture, where she focuses on domestic policy, including livestock and nutrition policy. Prior to her current position, she was Deputy Chief Economist at the House of Representatives Committee on Agriculture, where she handled agricultural economics, budget, and trade, as well as working on a range of agricultural, nutrition, and conservation policy issues. She was also previously a senior consultant at Informa Economics, focusing on strategic analysis for farm organizations and businesses on agriculture, transportation, and energy topics. Ms. McAdams received her Bachelor of Science in Animal Science and Agricultural Business Management from North Carolina State University and her Master of Science in Agricultural Economics from Texas A&M University.

Mary Ellen Mitchell-Whisnant
Chief of Staff

Mary Ellen Mitchell-Whisnant joined the USDA Office of the Chief Economist in 2021. In her role as Chief of Staff, she provides leadership for the day to day operation of OCE in addition to serving as an advisor and coordinator on strategic priorities for the Chief Economist and Deputy Chief Economist. Prior to joining OCE, Mary Ellen was the Acting Director for the Office of Community and Economic Development at the U.S. Treasury Department, where she also served as interim Executive Secretary during the 2017 Presidential Transition. In addition to her time at Treasury, she was also a Federal Financial Management Fellow in the Office of Management and Budget from 2018 to 2019. She began her federal career at the U.S. Environmental Protection Agency (EPA) and is a Returned Peace Corps Volunteer. Mary Ellen holds a BA in International Studies from Allegheny College and an MA, summa cum laude, in Public Management from The Johns Hopkins University.

Sharon S. Sydow
Senior Economist

Sharon Sydow is a Senior Economist in the Office of the Chief Economist (OCE). In OCE, her focus is on providing economic analysis of agricultural trade policies and market developments. She began her career with the U.S. Department of Agriculture (USDA) in 1991 at the Economic Research Service (ERS), where she was hired as the grains and oilseeds analyst for the Soviet Union. After the breakup of the Soviet Union, her research focused on agricultural trade and policy reform in Russia and other former Soviet countries. In 1998, she moved to USDA’s Foreign Agricultural Service (FAS) to work on multilateral trade negotiations at the World Trade Organization (WTO). In 2001, she was named Director for Agricultural Trade Policy in the Office of the U.S. Trade Representative (USTR), where she worked on a number of bilateral and multilateral agricultural trade issues. After several years of private sector work on agricultural trade issues, she returned to USDA in 2015 to work in OCE. She received her B.A. from Miami University (Ohio) and a Masters in International Affairs from Columbia University, where she also attended the W. Averell Harriman Institute for the Advanced Study of the Soviet Union.