Collecting global health data is an imperfect science: Workers tramp through villages to knock on doors and ask questions, write the answers on paper forms, then input the data — and from this messy, gappy information, countries and NGOs need to make huge decisions. Data geek Joel Selanikio talks through the sea change in collecting health data in the past decade — starting with the PalmPilot and Hotmail, and now moving into the cloud.