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58 August 31, 2006 2:55 Fortifying Six Sigma with OR/MS Tools
Six Sigma is well known to be a highly applied and result-oriented quality engineer-
ing framework and curriculum as compared to other programs such as the Certified
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Quality Engineer programs run by the American Society of Quality. The basis of its
strength does not lie in each individual tool but in the effective integration of the vari-
ous tools, with a strong emphasis on statistical thinking in the reduction of variability
in products and processes. However, as discussed in the preceding sections, tools and
techniques within the existing Six Sigma framework are inadequate to deal with many
problems in product and service delivery processes. In a bid to close the gap, a stronger
Six Sigma toolset containing OR/MS techniques capable of dealing with many of such
problems has been proposed. The linking and sequencing of the proposed tools are
driven towards a practical integration within the Six Sigma DMAIC framework.

5.4 CASE STUDY: MANPOWER RESOURCE PLANNING

This case study focuses on the application of the newly proposed OR/MS tools for
efficient manpower resource allocation. Some details associated with the Six Sigma
project have been deliberately left out for reasons of confidentiality. However, per-
tinent infomation relating to the analysis with the newly proposed OR/MS tool is
provided to demonstrate its effectiveness.
Here, we give an illustration of how the Six Sigma framework is applied to reduce
the waiting times for a retail pharmacy in a hospital. This investigation was prompted
by complaints about the long waiting times for drug prescriptions to be dispensed.
Initially, continuous efforts were made to expedite the work flow by the pharmacy
staff without a systemic examination of relevant work processes. These efforts turned
out to be insufficient in achieving the waiting time target set by the management for
the pharmacy.
In the Define phase, external Six Sigma consultants, together with the hospital
management, selected this particular project to reduce the waiting times of patients in
the central pharmacy given the urgency and proximity of the process to the customers.
Furthermore, as there were multiple satellite pharmacies with similar processes to
those of the central pharmacy, the project would be able to reap benefits beyond this
particular department. The success of this project would enable the Six Sigma team to
garner more extensive buy-in and support from the management and other hospital
staff. Such internal ‘marketing’ efforts are essential for sustainable implementation
and successful execution of future Six Sigma projects that will deal with increasingly
difficult problems.
Four major tasks were identified in the current process -- typing, packing, checking,
and checking and dispensing (or dispensing for short). The arrival rates of prescrip-
tions to the pharmacy were measured based on counts of arrivals each 10 minutes.
The profile of estimated arrival rates at each 10 minutes interval is shown in Figure
5.1. After accounting for outliers in the profile and reasons for high arrival rates in
some particular instances as shown in Figure 5.1, the profile was discretized and
two distinct arrival rates identified by visually examining the data. Although the
profile can be more accurately discretized by having additional segments, only two
distinct arrival rates were identified in preliminary investigations after accounting for
practical considerations related to manpower allocations and sources of variations,