2005). According to Sorensen (2001: 288), the CASMIN scheme, although following the theoretical principles and identifying qualitative differences, may also be associated with what may be called “stratum concept of class”, in that it groups individuals into strata according to the access they have to life opportunities or to a certain socioeconomic level derived from their position in the labor market. In this research, as will be detailed later, we use both the ISEI, as well as a classification of socioeconomic strata based on the CASMIN scheme.

The second strand of the mobility analysis, introduced by Blau and Duncan (2001) at the end of the 1960s, is focused on the analysis of occupational status attainment. It differentiates from the previous strand focusing on analysis at the individual level (rather than the analysis of the mobility system in society as a whole) and by its multivariate study of the stratification process that leads to individual attainment (Goldthorpe, 2005). Blau and Duncan (2001) proposed a model that analyzes the influence of origin (occupation and education of the father) on occupational attainment mediated by non-ascribed factors (education of the child and occupational status of the child in their first employment). This model allowed the differentiation and comparison of the effect of the ascribed (the social origin) and non-ascribed factors, with special emphasis on the effect of education on occupational destination (Ganzeboom, Treiman and Ultee, 1991; Blau and Duncan, 2001).

This strand of analysis was replicated by different researchers at an international level (Hout and DiPrete, 2006) and the proposed model has been the object of criticisms due to its oversimplification of the stratification process (Kerckhoff, 1995). In this sense, there have been efforts to account for additional factors which provide a more precise explanation of the mechanisms involved in the determination of the occupational attainment: Sewell, Haller and Portes (2001) and Sewell, Heller and Ohlendorf (1970) added psychosocial variables (mental or cognitive abilities, educational aspirations, influence of persons who are close), Kerckhoff (1995) argued in favor of the incorporation of institutional factors related to the educational institutions and the labor market and Lin (1999) and Kerbo (2006) refer to the studies that included variables related to social resources (social networks or social capital).

Empirical studies have identified factors that influence the association between occupational origins and destinations. It has been shown that the ascribed factors (sex, race, ethnic background and family characteristics of origin) are strong determinants of both educational and occupational attainment (Blau and Duncan, 2001; Hout and DiPrete, 2006). Furthermore, education is highlighted as the most important factor of occupational attainment, with the potential to equalize opportunities between the individuals; although it may also operate in ways that favor intergenerational inheritance. In this sense, it is argued that the characteristics of the educational system (how stratified, specialized-differentiated and decentralized it is and its degree of linkage with the labor market) influence educational attainment and labor results (Kerckhoff, 1995; Shavit and Müller, 1998) and that, due to the effect of the unexpected educational expansion, the differences related to the quality in education may have replaced the quantity of education in importance when assessing the labor market (Breen and Jonsson 2005, Kerbo 2006).

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