Help Optimal outpatient appointment scheduling tool

This calculator use a local search procedure that converges to the optimal schedule with a weighted average of expected waiting times of patients, idle time of the doctor and tardiness as an objective.
Because the local search procedure takes a very long time, two local search procedures where implemented.
- One with a smaller neighborhood, which don't guaranteed us to derive in the global optimum, but gives good results within a reasonable time.
- One with a big neighborhood, which guarantee us to derive in the global optimum, but computing time can be very large.
A user defined arrival schedule can also be validated.
The method of this tool is described in a HCMS publication.

Model

The model is a queuing system. The day/block length that a treatment/operation room is operational can be split in a number of equal intervals of some length (for example a day from 8.00AM till 4.00PM can be split in 48 intervals with length of 10 minutes). Within these intervals there should be scheduled a number of patients.
Our goal is to schedule these patients over those intervals in such a way that it minimizes the weighted average of expected waiting times of patients, idle time of the doctor and tardiness.
In the model we make the following assumptions:
- The service times of patients are independent and exponential distributed.
- Patients comes always right on time.
- Every patients has the same change of not comming at all (no-show).

Required Input

The input consists of:
- Average service time: The average time for a treatment
- Number of intervals: Total number of intervals
- Length of interval: in minutes
- Total number of arrivals: The total number of patients which must be treated
- Percentage no-shows: Which percentage of patients are not coming at all?
- alpha waiting: There isn’t the best way to choose weights. It depends on the objective. So if the main objective is to minimize the idletime of a doctor, than that factor must have a bigger weight.
- alpha idle time:
- alpha tardiness:

Output

The output consists of:
- Waiting time: This is the average time a patient is waiting for her/his treatment.
- Idle time: This is the average total time within the make span a doctor is waiting for a patient.
- Tardiness: The tardiness is the probability that the session exceeds the planned finishing time times the average excess.
- Fraction of excess: This is the probability that the last patient finish its treatment after the end of the working day/block.
- Make span: This is the average time in which all patients are been treated.
- Lateness: Day/block length -/- make span
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