From Knowledge@Wharton: The United Kingdom's Prime Minister David Cameron plans to create a national well-being index. French President Nicolas Sarkozy has formed a team that includes two Nobel Prize-winning economists to come up with a system for measuring the nation's well-being. In China, happiness indexes have become so popular that cities there compete for the title of China's happiest city. Many now argue that purely economic measures of a country's progress — such as gross national product (GDP) — fail to count many things people value highly, such as personal and community relationships or a healthy environment. To learn more about measuring happiness, Knowledge@Wharton spoke with Nic Marks, author of the e-book, The Happiness Manifesto: How Nations and People Can Nurture Well-Being.