  Surgery duration is usually used as an input to the operation room (OR)
allocation and surgery scheduling problems. A good estimation of surgery
duration benefits the operation planning in ORs. In contrast, we would like to
investigate whether the allocation decisions in turn influence surgery
duration. Using almost two years of data from a large hospital in China, we
find evidence in support of our conjecture. Surgery duration decreases with the
number of surgeries a surgeon performs in a day. Numerically, surgery duration
will decrease by 10 minutes on average if a surgeon performs one more surgery.
Furthermore, we find a non-linear relationship between surgery duration and the
number of surgeries allocated to an OR. Also, a surgery's duration is affected
by its position in a sequence of surgeries performed by one surgeon. In
addition, surgeons exhibit different patterns on the effects of surgery type
and position. Since the findings are obtained from a particular data set, We do
not claim the generalizability. Instead, the analysis in this paper provides
insights into surgery duration study in ORs.
