Measurement of cumulative trauma disorder risk in clerical tasks using fuzzy linear regression

Cumulative trauma disorders (CTDs) of the upper body have been identified as one of the fastest growing workplace hazards. The specific combination and significance of risk factors contributing to CTDs of the hand and forearm is still lacking, and developing methodologies to quantify the relationships of risk factors is greatly needed. Furthermore, the nature of CTDs and variability among individuals creates an environment where an array of uncertainty exists. The purpose of this research is to develop a fuzzy linear regression model to predict the relationship of known risk factors to the onset of CTDs. 27 keyboard users (22 for model building and 5 for model validation) participated in the study. Knowledge acquisition was performed through extensive literature analysis and interviews with two CTD experts. The model was constructed in a modular fashion with four fuzzy modules being constructed to represent the risk associated with the task, anthropometrics, joint deviation and personal factors. These modules were combined to represent an overall risk level and a final model for prediction of CTD risk. The results indicate that fuzzy linear regression is a useful technique for addressing the uncertainty associated with the definition and modeling of CTD risk factors.