I gave today’s opening keynote at the WWW Conference in Raleigh, North Carolina. My talk was about methodological and ethical issues involved in the study of Big Data, focusing heavily on privacy issues in light of public data. The first third focuses on four important arguments: 1) Bigger Data are Not Always Better Data; 2) Not All Data are Created Equal; 3) What and Why are Different Questions; 4) Be Careful of Your Interpretations. I then move into argue “Just because data is accessible doesn’t mean that using it is ethical,” providing a series of different ways of looking at how people think about privacy and publicity. I conclude by critiquing Facebook’s approach to privacy, from News Feed to Social Plugins/Instant Personalizer.