Table 12 Background variables (regressors) used in logistic regression models

Regressors: variables, (number of categories) and (reference) categories

 R1: Teachers group (3 categories)

  Teachers of general subjects in schools with no VET programmes (Group A)

  Teachers of general subjects in schools with VET programmes (Group D)

  Teachers of vocational subjects in schools with VET programmes (Group C and reference category)

 R2: Gender (2 categories)

  Male

  Female (reference category)

 R3: Age (2 categories)

  < 50 years

  50+ years (reference category)

 R4: Education (2 categories)

  ISCED 5B and below

  ISCED 5A and above

 R5: Permanency of the job (2 categories)

  Fixed term contract

  Permanent contract; (reference category)

 R6: Intensity of work (2 categories)

  Part time

  Full time (reference category)

 R7: Prevalence of students with a first language different from that of instruction (2 categories)

  10% or less

  More than 10% (reference category)

 R8: Prevalence of students with special needs in the school (2 categories)

  10% or less

  More than 10% (reference category)

 R9: Prevalence of students from disadvantaged homes in the school (2 categories)

  30% or less

  More than 30% (reference category)

 R10: Extent to which the lack of resources for professional development of teachers (PD) in the school limits principal effectiveness (2 categories)

  Not at all/very little

  To some extent a lot (reference category)