of gross national income ( _aid_ _~~g~~ ni_ _~~1~~ st_ ). Second, in recognition of the fact that lower levels of demand for reform in lower income countries may condition the policy influence that the World Bank can exert (Andrews 2011; Loayza et al. 2012), we include a measure of gross domestic product per capita ( _lngdp_ _~~p~~ c_ _~~1~~ st_ ). Third, to account for the possibility that the relationship between income and demand for reform is non-linear, we introduce the squared term of gross domestic product per capita ( _lngdp_ _~~p~~ c_ _~~1~~ st_ _~~2~~_ ).<sup>21</sup> Fourth, to address the possibility that small states lack bargaining power and may need to compensate for their own limited internal administrative and technical capabilities by relying on analysis, advice, and assistance from the World Bank (Vreeland 2003; Pop-Eleches 2009), we control for the size of a country’s population ( _lnpop 1st_ ).<sup>22</sup> Fifth, since democratically-elected governments are generally more motivated to “lock-in” reform commitments and more responsive to external pressures for reform (Kapstein and Converse 2008), we control for regime type, as captured by the POLITY rating ( _polity2_ _~~1~~ st_ ). Finally, to account for the possibility that a government’s political orientation influences the level of effort made by World Bank staff to convince the authorities of the merits of policy reform (Smets et al. 2013), we introduce a dummy variable that takes a value of 1 in country-years when the government in power has a left-wing orientation ( _left_ _~~1~~ st_ ). To measure these control variables in a way that minimizes the risk of endogeneity, we take the value of each measure during the first year in which a respondent held his or her public sector position.<sup>23</sup>

> 21Previous research suggests that middle-income countries have more “outside options” than low-income countries with respect to analytical and advisory service (IEG 2007: 5). Indeed, they often purchase analysis and advice from private sector entities. IEG (2008b: xvi) points to “economic monitoring ESW in [middleincome countries] that had access to such analysis from the private sector or international investors” as a particularly ineffective form of World Bank AAA, noting that “[t]he Bank’s economic monitoring ESW had very little value added in such circumstances.”

> 22The _lnpop_ _~~1~~ st_ , _lngdp pc 1st_ , and _lngdp pc 1st 2_ variables are logarithmically transformed to correct for their highly skewed distributions.

23As robustness checks, we calculate two alternative versions of our country-level controls by (a) using the mean of the observed values for the years in which a respondent held his or her public sector position, and (b) setting the values of these variables to those in the year prior to a respondents start year. The rationale for this approach (a) is to account for potential confounds over the full period of treatment. Imagine, for example, that GDP per capita increases sharply between a respondent’s start year and end year. If GDP per capita positively correlates with World Bank policy influence, and our control variable does not capture the fact that GDP per capita increased between the respondent’s start year and end year, we have omitted an important confound. The rationale for approach (b) is to minimize the risk of endogeneity by using 17