In PISA, a student’s socio-economic status is estimated by the PISA index of economic, social and cultural status (ESCS), a composite score based on three indicators: highest parental occupation, parental education, and home possessions. As no direct income measure has been available from the PISA data, the existence of household items has been used as a proxy for family wealth.
Highest parental occupation: Occupational data for both the student’s mother and the student’s father were obtained from responses to open-ended questions.
Home possessions: students reported on the availability of 16 household items at their home including three country-specific household items that were seen as local measures of family wealth within the country’s context. In addition, students reported the amount of possessions and books at home.
In Türkiye the three country-specific items in PISA 2018 were:
Air conditioning type heating-cooling system
TV subscriptions with payment
A holiday for at least one week in a year
Parental education: based on an internationally standardised transformation of the index of highest educational level of parents into years of education. The values used for each level of education are the median values observed in 2015 across all countries (OECD, 2018[1]).
In PISA the terms “advantaged students” and “disadvantaged students” refer respectively to those students coming from the top and bottom quartile of the ESCS scale.