The influence of students' home and family background on their academic success has been thoroughly investigated. Since the 1966 Coleman report (Hanushek, 2010), external factors affecting students' achievements have been extensively studied (Sirin, 2005). In his synthesis of meta-analyses on achievement, Hattie (2008) reports a significant effect size related to socioeconomic status (SES) of d=0.57. This considerable effect size indicates that any credible analysis of students' achievement should consider their background. In Slovenia, previous research (Cankar, 2020; Bren, Cankar & Zupanc, 2017) has shown that the transition to upper secondary education in Slovenia significantly highlights the effects of socioeconomic status (SES). While the differences in SES composition among schools are relatively small in lower secondary education, they increase markedly after the transition. Students from higher SES backgrounds tend to be drawn to the most demanding educational track, the "gymnasium," which leads directly to university studies, while other students opt for vocational tracks.

Although transitioning from vocational schools to tertiary education is possible, students from vocational track often lag behind their peers from general track in critical areas such as languages and mathematics. As these generic skills play a major role in success in tertiary education this situation raises equity concerns and necessitates a review of the educational system's procedures around this transition.

Performance disparities based on family wealth in Slovenia are minimal (OECD, 2017; p. 417) and the difference in scores between children of white-collar and blue-collar workers is average (OECD, 2017; p. 421). In contrast, Slovenia has one of the highest enrolment disparities in general versus vocational upper secondary programs based on socioeconomic status (SES) profile (OECD, 2016; p. 169) and a high index of social segregation between general and vocational schools (OECD, 2017; p. 423). To accommodate this conflicting information our study investigates the relationship between SES and the choice of upper secondary educational tracks among students in Slovenia. Specifically, it examines the relationship between SES and mathematics achievement for 14-year-old students selecting the most challenging general educational track, known as "Gymnasium."

This research highlights a significant impact of socioeconomic status (SES) on the academic trajectories of successive student populations, presenting previously unpublished findings. It underscores the importance of systematically and continuously monitoring SES to address emerging issues with evidence-based decisions.

We aim to investigate the interaction between the SES index and mathematics achievement with students' selection of the most rigorous general educational track ("Gymnasium") across three or four consecutive cohorts of Slovenian students. We will utilize national census data from the Slovenian Statistical Office and achievement data from the National Examinations Centre.

With the possibility to link data on achievement at the end of lower secondary education and family's socio-economic background to the choice of upper secondary educational track we are able to estimate relative strengths of both predictors and therefore demonstrate what plays bigger role in final choice.

Our research question would therefore be what are relative effects of SES and achievement in mathematics predicting choice of upper secondary track.

This research will be conducted under a contract with the Slovenian national statistics agency (Statistical Office of the Republic of Slovenia - SORS). We will use data on students from multiple cohorts, finishing their elementary school (9th Grade) in years 2017-2019. Data on mathematics achievement is available from National Examinations Centre, while the data on the socio-economic family background comes from Slovenian Statistical Office. Data is combined and anonymized and all analyses are made under strict security and confidentiality protocols (safe room, special data arrangements, etc.). For the analysis, we will use binomial logistic regression and transformational matrices.

The research results will demonstrate how SES and mathematical achievement are related to students' selection of Gymnasium. We expect that both predictors will show moderate effects, but the data from binomial regression analysis should demonstrate what - SES or Mathematics - is associated more with choice of educational track. Results will also show odds, associated with different values of both predictors, while transformational matrices will provide intuitively understandable probabilities of selecting each educational track. These results can exemplify a valid, systematic approach to educational improvement, as highlighted by Slavin (2002), where high-stakes decisions are informed by evidence and driven by relevant data. This could pave the way for the development of long-term educational governance as defined by Coward (2010). As many European countries have similar distinctions of ‘vocational’ and ‘academic’ upper secondary tracks this research and it’s finings are relevant also in an international context.

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