Comparative Government: Quantitative

• World Development Indicators, World Bank Best Bet
• International Historical Statistics, 1750- Best Bet
  Worldwide coverage of statistics, including population & vital statistics, labor, agriculture, industry, trade, transport & communications, agriculture, education, and national accounts.
• Human Development Report, United Nations Development Programme
• Statistical yearbook, United Nations
• World Integrated Trade Solution (WITS)
  "international merchandise trade, tariff and non-tariff measures (NTM) data. Browse the Country profile section to obtain countries exports, imports and tariff statistics along with relevant development data".
• National Accounts Main Aggregates Database, United Nations, Statistics Division. Choose Data Selection/Country Profile.
• Statistical Abstract of the United States.
  Formerly published by the U.S. Census Bureau. "Comprehensive summary of statistics on the social, political, and economic organization of the United States." A great place to start looking for data. Even if the data that you want are not there, look at the footnotes for relevant tables and the introduction to the relevant section for pointers to more comprehensive sources. Previous editions, 1878-, are also available.

Polls and surveys

• Global Attitudes and Trends, Pew Research Center
• World Public Opinion, Program for Public Consultation
• World Values Survey
  "The WVS consists of nationally representative surveys conducted in almost 100 countries which contain almost 90 percent of the world’s population, using a common questionnaire. The WVS is the largest non-commercial, cross-national, time series investigation of human beliefs and values ever executed, currently including interviews with almost 400,000 respondents. Moreover the WVS is the only academic study covering the full range of global variations, from very poor to very rich countries, in all of the world’s major cultural zones."

Finding aids

Governance and Institutional Quality

• Fragile States Index, The Fund for Peace, 2005- "An annual ranking of 178 nations based on their levels of stability and the pressures they face. The Index is based on The Fund for Peace’s proprietary Conflict Assessment System Tool (CAST) analytical platform. Based on comprehensive social science methodology, data from three primary sources is triangulated and subjected to critical review to obtain final scores for the Fragile States Index." "A reduced score indicates an improvement, just as a higher score indicates greater instability." Source: Fragile States Index 2016.
• Polity IV Individual Country Regime Trends, 1946-2013.  "Annual Polity scores have been plotted for each of the 167 countries currently covered by the Polity IV data series for the period 1946-2013 (trend graphs are also included with the Polity IV 2010 Country Reports). This version of the Polity Country Trend graphs display periods of "factionalism" and important Polity change events, including autocratic backsliding, executive auto-coup or autogolpe, revolution, collapse of central authority (state failure), and successful military coups."
• Freedom in the World: Aggregate and Subcategory Scores (online). See also print: 1978-1992 (with gaps), Main JC571 .F66. "Freedom in the World, Freedom House’s flagship publication, is the standard-setting comparative assessment of global political rights and civil liberties. Published annually since 1972, the survey ratings and narrative reports on 195 countries and 14 related and disputed territories are used by policymakers, the media, international corporations, civic activists, and human rights defenders to monitor trends in democracy and track improvements and setbacks in freedom worldwide."
• The Worldwide Governance Indicators, World Bank, "reports aggregate and individual governance indicators for over 200 countries and territories over the period 1996–2015, for six dimensions of governance: Voice and Accountability, Political Stability and Absence of Violence, Government Effectiveness, Regulatory Quality, Rule of Law, [and] Control of Corruption".
• According to the World Bank, the first list of fragile situations "was compiled in fiscal year 2006 and has gone through a series of changes in terms of classification from the Low Income Countries Under Stress List (LICUS) (2006-2009), to the Fragile States List (2010) to the now Harmonized List of Fragile Situations (2011-2015)." See the Information Note for the history of the classifications and notes related to comparability.
• Global Terrorism Index, Institute for Economics and Peace, "a comprehensive study analysing the impact of terrorism for 163 countries and which covers 99.7 per cent of the world’s population."
• Global Competitiveness Report 2019, World Economic Forum, featuring the Global Competitiveness Index which "provides a detailed map of the factors and attributes that drive productivity, growth and human development in the era of the Fourth Industrial Revolution".
• Data and Tools, International Institute for Democracy and Electoral Assistance (International IDEA)
• Corruption, Corruption Perceptions Index, Transparency International
• BTI Transformation Index
  "The Status Index ranks the countries according to their quality of democracy and market economy." "The Governance Index ranks the countries according to their leadership’s political management performance."
• Democracy Index, The Economist Intelligence Unit
  "The Economist Intelligence Unit’s Democracy Index is based on five categories: electoral process and pluralism; civil liberties; the functioning of government; political participation; and political culture. Based on their scores on 60 indicators within these categories, each country is then itself classified as one of four types of regime: full democracy; flawed democracy; hybrid regime; and authoritarian regime."
• Varieties of Democracy (V-Dem), Department of Political Science, University of Gothenburg, Sweden. "Varieties of Democracy (V-Dem) is a new approach to conceptualizing and measuring democracy. We provide a multidimensional and disaggregated dataset that reflects the complexity of the concept of democracy as a system of rule that goes beyond the simple presence of elections. The V-Dem project distinguishes between seven high-level principles of democracy: electoral, liberal, participatory, deliberative, egalitarian, majoritarian and consensual, and collects data to measure these principles."

Civil Society - Social, economic

• Ethnologue "contains information on 7,106 known living languages."
• Human Development Index, United Nations Development Programme. "A summary measure of average achievement in key dimensions of human development: a long and healthy life, being knowledgeable and have a decent standard of living."
• GINI index (World Bank estimate), World Bank. "Measures the extent to which the distribution of income (or, in some cases, consumption expenditure) among individuals or households within an economy deviates from a perfectly equal distribution."
• CIVICUS Civil Society Index (CSI). "A participatory needs assessment and action planning tool for civil society around the world."
• Mass movements database (in the works). Effective States and Inclusive Development, Global Development Institute, The University of Manchester.
• Multidimensional Poverty Index, Oxford Poverty & Human Development Initiative
• Report on the world social situation, prepared by the Bureau of Social Affairs, United Nations Secretariat, in co-operation with the International Labour Office [et al.]
  Main Ref HN17.5 .U46
• World Values Survey, "The World Values Survey [...] is a global network of social scientists studying changing values and their impact on social and political life".