Several studies have analysed the characteristics of the knowledge society, as well as its impact on the production of "official" statistics. In this paper we will not enter into this debate, but we will try to analyse the role of statistics in building a knowledge society and improving the democratic control of policy makers. This issue is especially important because the development of information and communication technologies (ICT) dramatically reduced the cost of producing statistics: therefore, nowadays a huge number of organisations is able to produce statistical figures and indices, frequently picked up by media, just for advocacy purposes and this contributes to create a sense of "confusion" often reported by citizens about the real state of the economy and of the society. This "noise" does not help at all citizens to make the best possible choices, including the electoral ones, and this is not a good thing for the functioning of economic markets and the democracy. The paper initially analyses the relationships between information, expectations and economic theory, as well as the nexus between information and political sciences. In the second part, various approaches to the measurement of societal progress and the role of "key indicators" are presented and analysed. Moreover, theoretical models and empirical evidence about what citizens know on societal progress are discussed. Finally, the OECD project on the measurement of societal progress is presented.