2.4. Statistical analysis
All data were analyzed with SPSS 16.0 for Windows. We calculated
both the person-based incidence rate of injury and the
event-based incidence rate of injury. The person-based incidence
rate referred to the number of workers with injury among all participating
workers and the event-based incidence rate referred to
the number of work-related injury events among all workers (one
worker could have several injury events in a year). The prevalence
rates of MSD in different body parts were calculated for all participants,
as well as by industry.
Binary logistic analysis with backward stepwise method was
used to estimate odds ratios (OR) and 95% confidence interval (CI)
of factors associated with injury cases and MSDs. Variables included
in the full model were gender, age, educational level, industry type,
duration of employment, work hours per week, mental stress at
work, previous work experience, previous history of injury. Only
variables with p value