טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentIsaac )Yizhaq( Balaila
SubjectA Dynamic Model for Determining Manpower Standards in
Service Jobs
DepartmentDepartment of Industrial Engineering and Management
Supervisor Professor Gilad Issachar


Abstract

Service jobs are jobs in which a worker supplies a service to a customer. Two factors create an inherent difficulty in determining time and manpower standards in service jobs: (a) The wide variation in Time Between Arrivals and in Service Performance Time (SPT); and (b) The difficulty of assessing the damage done to the organization by long customer Waiting Times (WT). This difficulty makes it hard to calculate the break-even point between raising worker output, which minimizes labor costs but increases customer WT, and improving service quality by lowering customer WT.


The model developed here, overcomes the above-mentioned difficulties, by determining indicators from three domains: 

1) Output - as measured by Level of Occupation (LO) of urgent tasks and by Total LO.

2) Service Quality - (a) Ratio of WT to SPT and to median WT; and (b) Maximum WT at three points on the WT axis : the 30%, 10% and 1% of customers with the longest WT.

3) Cost-Benefit - The cost of adding a worker relative to the decrease in WT at the margin.

   

For each indicator, the model recommends a performance range between two limiting values in accordance with the unique characteristics of the service sector branch being studied.


Simulation software has been developed to apply the model. Whenever the given number of workers cannot meet the indicator requirements (limiting values), the number of workers is altered and the model rerun. The recommended manpower standard is received when all requirements are achieved.


The model was tested on some service systems and the results proved more reliable than those obtained from work study or operations research alone.