KnowledgePanel®, created by Knowledge Networks, is an online Non-Volunteer Access Panel, in which potential panel members are chosen via a statistically valid sampling method and using known published sampling frames that cover 99% of the U.S. population. Sampled non-internet households are provided a laptop computer and free internet service. KnowledgePanel consists of about 50,000 U.S. residents, age 18 and older, including cell phone-only households and those who are of Hispanic origin that were selected probabilistically. In addition, the KN panel also includes approximately 3,000 teens age 13 to 17 whose parents or legal guardians have provided consent. The panel size fluctuates because of the addition of panelists from the on-going recruitment and because of voluntary withdrawals and retirements of panelists reaching the end of their panel tenure.