Variability, uncertainty & flexibility

Question 1

Unpredictable variability causes

Answer 1

Demand for service (fluctuating patients, severity, seasons, weather)
Provision of service (absenteeism of staff, technological problems, equipment/resources)

Question 2

Unpredictiable variability

Answer 2

Unsynchronised variability
Leads to queuing and reduces throughput

Question 3

Unexpected increased demand will lead to

Answer 3

Prioritizing
Longer waiting time
Higher workload
Increase in utilization

Question 4

Responses to unexpected increase in demand

Answer 4

Patients wait
Patients leave without being seen
Staff speed up by cutting corners
Staff works harder (higher staff turn-over in the long run)

Question 5

Variability buffering

Answer 5

All unpredictable variability will be buffered by a combination of inventory, capacity, time, quality & system degradation

Question 6

Variability buffering in service systems

Answer 6

No inventory, quality and system degradation are held constant
Trade off between variability, excess capacity & waiting times

Question 7

Queue pooling

Answer 7

Patients are helped by next available server
Dedicated server
Sharing a buffer reduces the total amount of buffering needed
Reduces waiting times
Flexible capacity needed (cross-trained staff)

Question 8

Capacity pooling

Answer 8

Off-service placement of hospital patients
Fewer beds required (less excess capacity)
Flexible capacity needed (cross trained staff)
Off service placement leads to longer LoS and lower QoC

Question 9

Safety tipping point

Answer 9

If occupancy increases to moderately high levels, QoC can largely be maintained
If occupancy increases further, buffers are depleted & the system can no longer cope leading to errors / cutting corners

Question 10

Hypothesis 1

Answer 10

Congestion Effect
As occupancy near the time of expected discharge increases, LoS increases

Question 11

Hypothesis 2

Answer 11

First tipping point, speed up
Tipping point at moderately high occupancy levels
LoS on day of expected discharge date becomes shorter as occupancy rises

Question 12

Hypothesis 3

Answer 12

Second tipping point, saturation
Second tipping point at very high occupancy levels, where LoS of patients approaching day of expected discharge becomes longer as occupancy increases