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.     

DO LABOR MARKETS PROVIDE ENOUGH SHORT-HOUR JOBS? AN ANALYSIS OF WORK HOURS AND WORK INCENTIVES

This paper examines the role that work incentives play in the determination of work hours. We use a conventional efficiency wage model to analyze how firms respond to worker preferences regarding wage-hours packages. In contrast to previous work, we study markets in which workers have heterogeneous preferences. In this context we demonstrate that job offers will specify both wages and work hours and many individuals will not be able to work their preferred number of hours. We show that the labor market equilibrium may be characterized by a less than optimal number of short-hour jobs.     

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.