(e.g. the Institutional Profiles Database and the Cingranelli-Richards Human Rights Database), or because the methodology of the data source has changed so that it no longer meets the criteria for inclusion in the WGI (e.g. selected components of the Heritage Foundation Index of Economic Freedom, or the European Bank for Reconstruction and Development Transition Indictors, see footnote 7). We do however continue to use these dropped data sources in the WGI for the years for which they were available and suitable for the WGI (see Table 1).

We assign variables from the 35 data sources described above to each of these six governance dimensions. For example, an assessment of the quality of the bureaucracy would be assigned to Government Effectiveness, a question about confidence in the police or the courts would be assigned to Rule of Law, and a question about the perceived likelihood of having to pay a bribe would be assigned to Control of Corruption. In some cases, a single data source will have multiple questions that can be assigned to the same dimension. In this case, we use the average across all relevant questions from that data source.<sup>13</sup> Finally, we only assign each question from each data source to only one of the six governance dimensions, selecting the dimension that best matches the content of the question. Annex 2 in this paper provides a complete list of all the questions from each of the data sources assigned to the six aggregate indicators in the most recent year that the source appears in the WGI. As the specific questions available in each data source may vary over time, we also report the full list of questions assigned to each of the six governance dimensions over time at www.govindicators.org.

Naturally, the process of assigning questions to governance dimensions involves some judgment, including on whether the question – or even the data source itself – should be used at all, and if so, to which of the six governance dimensions it should be assigned. The definitions of the six dimensions of governance themselves also involves some judgment, and alternative conceptualizations of governance might lead to a larger or smaller number of dimensions with potentially different structure than what we use in the WGI. We recognize that there is no single outcome for many of these decisions that will be satisfactory to all users of the WGI. For this reason, the WGI website allows users to access the source

> 13 We do this for the following technical reason.  As discussed in Section 3 below, the statistical methodology we use to combine the individual indicators from many individual data sources into aggregate indicators is based on the assumption that each data source within a governance cluster bring independent information on the concept of interest.  This assumption would be difficult to justify if the list of individual variables entering into one of the governance clusters contains multiple questions from the same data source, that may very well be scored by the same analyst (in the case of expert assessments).  To avoid this, we simply average together multiple questions from the same data source and treat them as a single variable when constructing the aggregate indicators.  See also Section 5.1 below where we discuss the possibility that measurement error might be correlated across data sources.

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