Breaking the Waves? Education, Youth Bulges, and Armed Conflict reference to the definitions valid in 2000, regardless of different conventions at the time.

On the other hand, the IIASA dataset comes with limitations of its own. A significant number of countries is not included, and – especially relevant to the present study – since it is difficult or impossible to conduct an effective census in unstable countries, exclusion from the list is likely to correlate with the occurrence of conflict.

Another limitation lies in the necessity to make more or less well-justified assumptions regarding firstly the education profile of migrants, and secondly the age at which educational transitions occur. While the transition to primary education can be assumed to occur before the age of 15 for the vast majority of those who do make it, the proportion of lower secondary completions occurring before and after the age of 15 must be estimated. The range of ages of transition to tertiary education is even greater, especially in many developing countries.

While these assumptions regarding the exact age of transition may not be critical when analyzing the effect of the education profile of the entire labor force on economic growth, say, an analysis dealing with youth, i.e. focusing on the ages at which the transitions tend to occur, is more sensitive to them. An additional complication lies in the definition of the education levels. Mapping all possible educational attainment levels to 4 categories necessarily means some distinctions are blurred. The mapping in the IIASA data means that all those with any primary schooling but who never completed lower secondary school fall into level 2. As a result, individuals can be registered as being at level 2 even if they only attended primary school for a year, and are for all practical purposes (and for the purposes of the present analysis) indistinguishable from the lowest attainment level.

To mitigate the impact of the above, the present study focuses primarily on the effect of secondary schooling. This means it is unaffected by the blurring between the bottom two levels and by the problematic assumptions regarding the age of tertiary completion. The principle education variable analyzed is the proportion of 20-24 year-old males in the two higher attainment categories, i.e. having _at least_ completed lower secondary school. Even though the values for males and females are highly correlated (Pearson's correlation coefficient > 0.95), the value for males is chosen on account of reflecting more closely the theoretical considerations that it is specifically young men who contribute to conflict potential. This indicator is robust to the exact timing of the transition from ‘some primary’ to ‘completed lower secondary’, because all of these are assumed to have occurred by age 20.

We have constructed additional education variables to test more specific claims in the youth bulge and conflict literature. _Progression ratios_ from primary to secondary education are defined as the percentage of males aged 15-19 with secondary or higher education of all males aged 15-19 with primary or higher education. Similarly, progression ratios from secondary to tertiary education are defined as the percentage of males aged 24-29 with tertiary education as a share of all males aged 24-29 with secondary or higher education. _Expansion in secondary education_ among males aged 15-24 is defined as the number of males with secondary education aged 15-24 at time t less the number in the same category in period t-1, normalized over the total male population aged 15-24 at time t. Similarly, expansion in tertiary education among males aged 20-29 is defined as the number of males with tertiary education aged 20-29 at time t less the number in the same category in period t-1, normalized over the total male population aged 20-29 at time t. Figures 1 and 2 illustrate trends in primary and secondary male educational attainment respectively, globally for Sub-Saharan Africa. Sub-Saharan Africa is trailing well below the rest of the world in secondary educational attainment, although there is considerable inter-regional and cross-country variation 9