Evaluation with One Eye Closed: The Empiricist Agenda in Social Work Research

Please address requests for reprints to Peter Raynor, Centre for Applied Social Studies, University College of Swansea, Singleton Park, Swansea SA2 8PP. Summary This paper was originally presented at a conference on ’theeffectiveness of social work‘ at Swansea in 1981. It arguesagainst a narrowly empiricist model of evaluation in socialwork, suggesting that while such a model may help to improvethe technical efficacy of methods, it can tell us little aboutthe desirability of the goals towards which our methods aredirected, or the social functions which they serve. The finalsection points to some possible resources for rational discussionof areas which ’scientific‘ models of evaluationtend to neglect.     

The Enduring Relevance of Case Management

Correspondence to Peter Ryan, School of Health, Biological and Environmental Sciences, Middlesex University, Archway, 7, Highgate Hill, London N19 5NF Summary This article summarizes the main results and policy implicationsof a Department of Health funded mental health case managementresearch and development project. The project implemented casemanagement services in four different sites, and worked withclients who were severely disabled with long-term mental illness.Higher levels of engagement (95 per cent) were achieved by case-managedas compared to control clients. They were also linked to a widerrange of community services. However, costs of the experimentalservices were higher, and client outcome variable. In two sites,case-managed clients achieved significant improvements in psycho-socialadjustment, whereas on the third site, there were no differencesin outcome between the control andexperimental clients. The article concludes that case management continues to be amode of service delivery which can achieve real benefits forclients in terms of preventing them from falling through thenet, and in linking them in responsive ways to community services.However, the increased costs can make it an unattractive optionfor purchasers, and ways need to be found to retain the establishedbenefits, whilst reducing the costs to service purchasers.     

AN IMPROVED HEURISTIC FOR STAFFING TELEPHONE CALL CENTERS WITH LIMITED OPERATING HOURS

Many telephone call centers that experience cyclic and random customer demand adjust their staffing over the day in an attempt to provide a consistent target level of customer service. The standard and widely used staffing method, which we call the stationary independent period by period (SIPP) approach, divides the workday into planning periods and uses a series of stationary independent Erlang‐c queuing models—one for each planning period—to estimate minimum staffing needs. Our research evaluates and improves upon this commonly used heuristic for those telephone call centers with limited hours of operation during the workday. We show that the SIPP approach often suggests staffing that is substantially too low to achieve the targeted customer service levels (probability of customer delay) during critical periods. The major reasons for SIPP‘ s shortfall are as follows: (1) SIPP's failure to account for the time lag between the peak in customer demand and when system congestion actually peaks; and (2) SIPP’ s use of the planning period average arrival rate, thereby assuming that the arrival rate is constant during the period. We identify specific domains for which SIPP tends to suggest inadequate staffing. Based on an analysis of the factors that influence the magnitude of the lag in infinite server systems that start empty and idle, we propose and test two simple “lagged” SIPP modifications that, in most situations, consistently achieve the service target with only modest increases in staffing.     

INSIGHTS ON SERVICE SYSTEM DESIGN FROM A NORMAL APPROXIMATION TO ERLANG'S DELAY FORMULA

We show how a simple normal approximation to Erlang's delay formula can be used to analyze capacity and staffing problems in service systems that can be modeled as M/M/s queues. The numbers of servers, s, needed in an M/M/s queueing system to assure a probability of delay of, at most, p can be well approximated by s ≅ p + z_***I-p+, where z_1-p, is the (1 - p)th percentile of the standard normal distribution and ρ, the presented load on the system, is the ratio of Λ, the customer arrival rate, to μ, the service rate. We examine the accuracy of this approximation over a set of parameters typical of service operations ranging from police patrol, through telemarketing to automatic teller machines, and we demonstrate that it tends to slightly underestimate the number of servers actually needed to hit the delay probability target—adding one server to the number suggested by the above formula typically gives the exact result. More importantly, the structure of the approximation promotes operational insight by explicitly linking the number of servers with server utilization and the customer service level. Using a scenario based on an actual teleservicing operation, we show how operations managers and designers can quickly obtain insights about the trade-offs between system size, system utilization and customer service. We argue that this little used approach deserves a prominent role in the operations analyst's and operations manager's toolbags.     

THE PERILS OF EXCELLENCE: BARRIERS TO EFFECTIVE PROCESS IMPROVEMENT IN PRODUCT-DRIVEN FIRMS

Several authors have suggested that a focus on manufacturing capability and on continued process improvement may be a powerful source of competitive advantage, yet many firms appear to have encountered great difficulties in taking advantage of this insight. This paper reports on the results of five these conducted under the auspices of the MIT Leaders for Manufacturing program at the Microwave Technology Division of the Hewlett-Packard Company. We found considerable evidence that the marginal returns to process development within the division were probably considerably higher than the division's cost of capital, suggesting that process improvement probably was underfunded despite the fact that improving manufacturing capability had been identified as a key strategic priority. We found no evidence that this “underfunding” reflected either a failure to recognize the problem or an overly hierarchical or rigid organization. Rather it appeared to flow from the historical strengths of the division. A devotion to leading-edge technical solutions and to immediate customer service at almost any price had created barriers to the effective funding of process improvement that were deeply rooted in the organizational structures, information systems, and formal and informal incentive structures that had evolved to support the division's historical emphasis on excellence on product design. Our results highlight the problems that very successful product-driven companies may encounter in attempting to make continual process improvement central to their strategic mission.