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Case Study: Manpower Resource Planning 63
Table 5.5 Comparisons of sojourn times for each process and mean total
waiting times.
Type of job Without screening With screening
Screening -- 2.6 (1 pharmacist)
Typing 0.6 (2 typists) 0.6 (2 typists)
Packing 5.9 (10 packers) 5.6 (10 packers)
Checking 6.2 (1 pharmacist) 5.0 (1 pharmacist)
Dispensing checking* 9.0 (8 pharmacists) 2.0 (7 pharmacists)

Mean total waiting time 21.7 15.8

*Service times only

process). It was expected that this would help to alleviate problems associated with
errors in prescriptions and medicine shortages.
A pilot run was implemented with one dispensing pharmacist moved to the newly
implemented screening process. Such a reconfiguration would not require additional
pharmacists to be hired. Service and arrival rates estimates were obtained from the
pilot runs and mean waiting times predicted for each process. The mean total waiting
times for prescriptions can again be computed by summing all the mean waiting and
service times of each process. The average waiting times computed were statistically
validated with actual data obtained from pilot runs.
Table 5.5 shows the improvements in the average sojourn times of each subprocess
and the mean total waiting time for processes before and after the addition of the
screening process. Improvements can be observed in the new process because many
interruptions that occurred during the dispensing process were effectively reduced
by the screening process upfront. As a result, the productive time of pharmacists
increased and the mean queue length in front of the dispensing process shortened
from 13 to 3.
Various possible system configurations were again tried with different number
of packers and dispensing pharmacists with the new model that considered the
screening process. In order to ensure finiteness of steady-state waiting times, at least 8
packers and 7 dispensing pharmacists for the packing and “checking and dispensing
processes respectively are needed. From the analysis, the proposed new configuration
was found to be more robust to changes in manpower deployment over the packing
and dispensing subprocesses (see Figure 5.5). Eventually, this new robust design
was adopted to ensure waiting-time stability over possible variations in manpower
deployment.
Process validations on results generated from the mathematical models depicting
original and improved processes have been dealt with throughout the Analyze and
Improve phases in the preceding discussions. At the final Control phase, standard
operating procedures (SOPs) were put in place in order to ensure stability the of new
processes. During the generation of these SOPs, several new control measures were
proposed by the team and implemented with the understanding and inputs from the