Big Data and New OpportunitiesExample: Google Flu TrendsTarget Population, Access Frame, and SampleExample: What Makes Members of an Online Community Active?Example: Who Will Win the Election?Example: How Do Environmental Hazards Relate to an Individual’s Health?Instruments and ProtocolsMeasuring Natural PhenomenaExample: What Is the Level of CO2 in the Air?AccuracyTypes of BiasTypes of VariationSummary