Refining Square Root Safety Staffing by Expanding Erlang C.

C.A.J.E.M. Janssen, J.S.H. van Leeuwaarden, A.P. Zwart

Research output: Contribution to JournalArticleAcademicpeer-review


We apply a new corrected diffusion approximation for the Erlang C formula to determine staffing levels in cost minimization and constraint satisfaction problems. These problems are motivated by large customer contact centers that are modeled as an M/M/s queue with s the number of servers or agents. The proposed staffing levels are refinements of the celebrated square-root safety-staffing rule and have the appealing property that they are as simple as the conventional square-root safety-staffing rule. In addition, we provide theoretical support for the empirical fact that square-root safety-staffing works well for moderate-sized systems. © 2011 INFORMS.
Original languageEnglish
Pages (from-to)1512-1522
JournalOperations Research
Issue number6
Publication statusPublished - 2011


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