Psychometric Development and Validation of the Nigerian Secondary School Student Psychological Safety Scale

This study undertakes the systematic development and comprehensive psychometric validation of the Nigerian Secondary School Student Psychological Safety Scale, an original measurement instrument designed to assess students' sense of psychological safety within the secondary school classroom environment across Nigeria's diverse cultural and educational contexts. Psychological safety, the belief that one can express oneself, make mistakes, and seek help without fear of humiliation or punishment, is emerging as a critical but under-measured construct in educational psychology, particularly in contexts characterised by authoritarian pedagogical traditions. No validated instrument exists for assessing this construct specifically within Nigerian secondary school populations. The study follows the Standards for Educational and Psychological Testing instrument development protocol across five phases: construct definition and domain mapping through literature synthesis and focus groups with 120 students across five geopolitical zones; item generation involving 35 content experts; pilot testing and item analysis with 350 students; large-scale validation with a nationally representative sample of 1,400 secondary school students from 28 schools across all six zones; and longitudinal predictive validity testing over one academic year. Exploratory and confirmatory factor analyses, multi-group invariance testing, item response theory calibration, and criterion validity testing against academic engagement and well-being measures are conducted. Results support a four-factor structure encompassing voice safety, error safety, help-seeking safety, and identity safety, with robust psychometric properties across gender, school type, and geopolitical zone. The scale demonstrates strong predictive validity for academic engagement. This instrument constitutes an original psychometric contribution to the field. Keywords: psychological safety, psychometric development, secondary school, measurement, Nigeria.