Our solution for a nurse rostering problem with data from the International Nurse Rostering Competition. This case was done for an Operations Research class at the Tepper School of Business.
2. Allocating nurses optimally
Feyer, gopalratnam, mccarthy, and reese
01. Difficult real-world problem
Many current paper-based approaches
are not provably optimal or do not
consider all constraints.
02. nurse rostering competition
Partial solution using actual competition
data but in a limited time window.
03. Realistic framework
Solution includes all data types and
constraints specified in competition rules.
3. Hospitals have many needs
Hard constraints Soft constraints
Each nurse can only work once per day
Minimum staffing needs
Feyer, gopalratnam, mccarthy, and reese
Consecutive shifts rules
Each nurse must have requisite skills
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4. Nurses have many requests
Hard constraints Soft constraints
Optimal staffing needs
Min / max consecutive days on / off
Nurse shift preferences
Feyer, gopalratnam, mccarthy, and reese
Work full weekend
Min / max number of work days
Max number of working weekends
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5. sets and parameters are straight forward
Nurse parameters
Feyer, gopalratnam, mccarthy, and reese
• Shift preferences
• Skill sets
• Contract type
Contract parameters
Hospital parameteres
N D,T
S,Z
R C
• Min / Max consecutive days on
• Min / Max consecutive days off
• Min nurses per skill per shift
• Goal of minimizing penalties
6. constraints require some finesse
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Nurse cannot work more than 5
consecutive days.
Nurse cannot be off less than 2
consecutive days.
If a nurse works Saturday, the
nurse should also work Sunday.
Feyer, gopalratnam, mccarthy, and reese
7. Solution with 30 nurses after one hour
Feyer, gopalratnam, mccarthy, and reese
8. Interesting insights from the solution
Feyer, gopalratnam, mccarthy, and reese
9294
variables
510
780
Total penalty when objective is to
minimize the maximum penalty
on any one nurse, then to
minimize the overall penalty.
Objective value of main
problem. Total penalty is 300
for entire roster plus 210
spread across 3 nurses.
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Constraints
>1 hr
solve time
9. Expand the problem going forward
week one week two week three
Penalty ρ1
Feyer, gopalratnam, mccarthy, and reese
Penalty ρ2 Penalty ρ3
Penalty for ≤ 2 or ≥ 6
consecutive days worked
can be met across periods.
Complete problem includes datasets
for 120 nurses. Computation time
grows non-linearly.
Long term objective is to minimize
Σρi which may result in suboptimal
allocations in some periods.