Table 1.

Description of Educational Levels.

Level	Verhage categoriesa
Low	1. Less than 6 years of primary education
	2. Finished primary education
	3. Primary education and less than 2 years of low-level secondary education
	4. Finished low-level secondary education
Middle	5. Finished average-level secondary education
High	6. Finished high level secondary education
	7. University degree

^aAdapted from Verhage (1964).