Education Search Trees
The education level of WageIndicator respondents is measured with the question: ‘What is the highest level of education you have attained (with certificate)?’. For school pupils or students, the question is: ‘At what stage of education are you at the moment?’.
The questionnaire uses search trees to generate response options for these questions. Each country-specific search tree consists of a list of the most common national educational categories, including outdated forms of education if these are still prevalent in the workforce. Thus, for example, a 50-year employee who completed a qualification that has since been replaced by another can still find the appropriate item amongst the response options. For most countries, a 1-level search tree is sufficient (educat1), but for a number of countries, a 2-level search tree is in use (educat2). For the Netherlands, a 4-level search tree identifies in great detail the nationally accredited educational categories.
To facilitate cross-country comparisons, for all countries the national educational categories identified by WageIndicator are recoded into the worldwide International Standard Classification of Education classification 1997, as designed by UNESCO. While all efforts are made to locate official assessments of ISCED levels for each educational category, in instances where these determinations are not available, an estimate is made by applying the classification criteria set down by UNESCO to what is known about the educational category in question, drawing upon reference sources and interviews with local experts where possible. Where possible, the search trees also contain information regarding the approximate time required to complete a particular level of education, the age at which it is likely to be completed, and its orientation, whether vocational, general or both (please see Explaining the dataset for more information).