Why do the WGI show margins of error with country scores?
All measures of governance and the investment climate are unavoidably imprecise. The WGI capture this imprecision by showing margins of error with countries scores that capture the statistically-likely range of values of governance. These margins of error reflect the extent of agreement among the underlying data sources: when data sources tend to agree, the margins of error are smaller, and when they disagree, margins of error are larger. Margins of error are also smaller for country estimates based on more data sources. For example, margins of error for a country estimate based on just one data source would be more than twice as large as for a country estimate based on five data sources. A typical country estimate in the WGI data in recent years is based on 11 separate data sources. These margins of error reflect the reality that governance is difficult to measure using any kind of data. In most measures of governance or the investment climate they are however left implicit or ignored
