secondary enrollment rates, there are ceilings of 100% to contend with.<sup>4</sup> For the measure we have adopted here, namely, years of education completed by adults over 15, there is no formal ceiling but the fact remains that, once a large fraction of a population has received, say, secondary education, it is harder to get further increases in the average level of education. On the other hand, it could be argued that countries with low levels of education to begin with may be too poor to address their education needs and so may find it harder to increase education levels, suggesting the presence of a “poverty trap” phenomenon. Which pattern prevails will depend on whether or not we are able to control for variables that reflect the availability and use of public and private resources to attain more education.<sup>5</sup> _Growth of income:_ The average growth of per capita income is relevant because it proxies for (a) the availability of private resources to spend on education and (b) provided there is an effective tax system, the availability of public resources with which to build schools, hire teachers and pay for related education inputs. All other things being equal, the faster income grows in a country, the faster one might expect it to increase education attainment. The measure used in the regressions below is the average growth rate during 1970-2010 of income per capita in 2005 PPP dollars.

_Children’s health_ : The effective demand for education may also be affected by such factors as children’s health. Children who are less healthy for any reason are likely to be absent for more days from school, to repeat grades and to drop out at higher rates and earlier ages. An important determinant of children’s health is likely to be their food intake. In the empirical work reported below, we use the prevalence of undernourishment in the general population to proxy for children’s health status.<sup>6</sup> This measure is available in the World Development Indicators (WDI) database starting from 1991 and so the average value for the period 1991-2010 is used in the empirical analysis.

_Public spending on education_ : This is a more direct measure of public resources devoted to increasing education inputs. We expect higher levels of spending to be associated with higher levels of education attainment. This is expected to be of special relevance to the MENA region because most countries there had adopted a model of publicly financed and delivered provision of education by the 1960s and continued to implement this model into current times. Lebanon is possibly the only MENA country where the private sector has historically had a more prominent role than the public sector in education services. In the regressions that follow, we use the level of public spending on education per capita per year (in 2005 PPP dollars) averaged over 1990-2010.

4 Sometimes gross enrollment rates of above 100% are encountered. This means that the numerator (number enrolled) exceeds the denominator (number of children in the relevant age group). This can happen when children above the relevant age group remain among the enrollees because they are repeating grades or are returning to school after an absence.

5 The relationship could also be modelled as an S-shape curve capturing the idea of slow rates of change at very low and very high levels of education and faster rates of change in between (see Clemens et. al, 2007 for a discussion.) We have not pursued this idea in this paper.

> 6 The measure refers to the proportion of the population whose food intake is insufficient to meet minimum dietary energy requirements continuously. The statistical methodology note in the WDI database describes the data as measuring “food deprivation based on average food available for human consumption per person, the level of inequality in access to food, and the minimum calories required for an average person.”

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