In addition to differences in geographical coverage, the microdata-based databases also differ in the manner of their construction, and even in their primary purpose. LIS’s primary objective, for example, is to provide researchers with access to _harmonized microdata_ (the Luxembourg Income Study Database and Luxembourg Wealth Study Database) through their remote execution software, LISSY. In addition, LIS does regularly publish a set of Key Figures with inequality measures for post-tax and transfer income for (mainly) high-income countries. The Key Figures report measures such as the Gini Coefficient, Atkinson Coefficient and 90/10 ratio, calculated by LIS researchers using the harmonized microdata contained in the Luxembourg Income Study Database.<sup>4</sup> Although for the purposes of this special issue, the focus is on LIS’s Key Figures (Ravallion, 2015), it should be clear that they are not the institution’s primary focus (Gornick et al., 2015) The IDD, on the other hand, is a data set created by the OECD from household surveys, tax registers and administrative records received from National Statistical Offices (NSOs), ministries or research institutes of OECD member countries. Calculations are based on a standardized questionnaire, which is designed by the OECD to achieve comparability across countries. The OECD does not actually calculate these summary statistics in-house: the database is comprised of indicators sent by country data providers, who compute them using their own micro-data. The two primary databases focused mainly on rich countries – LIS and IDD – are therefore very different in purpose, construction and nature.

CEPALSTAT and SEDLAC are both focused on Latin America and the Caribbean. CEPALSTAT is the statistical database of the United Nations Economic Commission for Latin America and the Caribbean. CEPALSTAT includes a wide range of data and a variety of economic, sociodemographic, and environmental measures for the region, including inequality and poverty estimates. SEDLAC provides statistics on poverty and inequality in Latin America and the Caribbean. It is compiled by a partnership between the Center for Distributional, Labor, and Social Studies at the Universidad Nacional of La Plata (CEDLAS - UNLP) and the World Bank’s Poverty Global Practice.<sup>5</sup> In both cases, all statistics are computed directly from microdata.

_Group 2: Secondary Source Data Sets_ Two of the eight databases are created from inequality measures estimated by other researchers. WIID is a data set administered by UNU-WIDER that collects inequality estimates from a number of sources, including published research papers and primary databases, such as those discussed above. It is global in scope, and often reports multiple entries for the same country and year, sometimes with different welfare concepts (e.g. disposable income versus consumption) and sometimes from different sources. WIID was initially created in the late 1990s, for a specific research project conducted jointly

> 4 The LIS Key Figures website provides the STATA and SPSS code used to calculate the summary statistics, so as to enable researchers to test the sensitivity of these statistics to various parameter choices regarding, for example, weights, equivalence scales, top coding, etc.

> 5 Through this partnership, SEDLAC is actually the source of data from Latin America and the Caribbean into PovcalNet / WDI.

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