At Quantcast we have access to multiple complementary data sources. We have several clickstream data sources that allow us to calibrate our cookie correction models. Quantcast Measure captures billions of media consumption events every month. What’s more, many of our Quantified sites share anonymous identifiers with us that are independent of cookies. This mass of data – with different collection processes, biases and issues — allows us to effectively “triangulate” and develop dynamic, and accurate projections. For additional insights into how our model works see our Cookie Corrected Audience White Paper.