 The provision of public goods is often associated with market failure due to the externalities created by the public good. Suppose that in a two-by-two toy economy Bob and Sally decide how much to invest in a discrete public good G such as a radio station. Both have an initial endowment of a private good (which functions as money in this economy). The public good will be produced \((G = 1)\) if the sum of contributions \(g_{\textrm{Bob}}\) plus \(g_{\textrm{Sally}}\) is higher than the production cost c. Thus (Varian 1992: 415):