Absenteeism impairment = days off work × 5

Presenteeism impairment = presenteeism score × (20 - days off work) Work impairment percentage = absenteeism impairment × presenteeism impairment (1)

Productivity costs were calculated by multiplying the overall work impairment percentage by the average Australian mining annual salary of \$134,784 [30]. Finally, independent sample t-tests and

a one-way ANOVAs were performed to examine the differences in productivity costs depending on employee characteristics and stage of change.
