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Case Study: Manpower Resource Planning 59
Arrival Rates Profile
6 5 Outlier
Estimated Arrival Rates (prescriptions/ min) 4

3

2

0 1
100 200 300 400 500 600
Time (mins)

Figure 5.1 Profile of estimated arrival rates.

such as day-to-day variations, in the arrival rates. Furthermore, subsequent sensitivity
analysis based on different arrival rates using queuing methodologies will allow us
to select the most robust manpower configurations for each distinct arrival rate.
With reasonable estimates of data on the arrival rates extracted from the arrival rate
profile shown in Figure 5.1, together with service and rework rates shown in Table 5.4
obtained in the Measure phase, the lead times and value-added times for each process
can be computed. The entire process can in fact be represented by an open queuing
network as shown in Figure 5.2.

Table 5.4 Service and rework rates.
Process Estimated service rates (min/job)

Typing 1.92
Packing 0.20
Checking 1.70
Checking and dispensing 0.19
Rework routing Estimated proprotion of rework

Packing→Typing 0.025
Checking→Typing 0.025
Checking→Packing 0.025
Checking and Dispensing→Typing 0.001
Checking and Dispensing→Packing 0.001