1 Department of Business Administration, Gies College of Business, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA. ukm@illinois.edu.
2 Department of Electrical and Computer Engineering, Grainger College of Engineering, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA.
3 Department of Business Administration, Gies College of Business, University of Illinois at Urbana Champaign, Urbana, IL, 61801, USA.
4 School of Information, University of California Berkeley, Berkeley, CA, 94720, USA.