Stratified statistical analysis for effectiveness evaluation of frontline worker safety intervention: Case study of construction steel fabrication

Abstract

Frontline employees play a key role in implementing and maintaining onsite safety programs and techniques. Evaluations of the effectiveness of ongoing safety interventions, however, have relied on the subjective judgment of supervisors. Through a case study, this research aims to explore practical measures to assess the effectiveness of safety interventions (i.e., pre-task planning and worksite inspection) implemented at the frontline level. With the data collected from construction steel fabrication shops, a Poisson regression model integrated with stratification analysis is proposed to identify the relationships between performance measures and incident records; consider confounders and effect modifiers such as age, experience, and task types; and adjust the influence of the third variables on the regression analysis. The results show that content coverage rates, longhand description, and safety communication times are statistically related to incident reduction (p-value <0.01). In addition, stratum analysis reveals the effectiveness of handwritten forms for less experienced foremen (<19 years) and highlights the importance of providing sufficient time for safety communication among juniors (<35 years old).