CiteULike: Tag cost

Stress and the evolution of condition-dependent signals

Katherine Buchanan — 2008-01-23T03:24:37-00:00

Trends in Ecology & Evolution, Vol. 15, No. 4. (1 April 2000), pp. 156-160.

Stressful events are known to initiate a cascade of physiological mechanisms that are potentially costly for metabolic processes. Although these mechanisms are well understood, the long-term costs and the potential implications for individual condition and behaviour have been considered only recently. Combining information from physiological, ecological and behavioural studies can help us to understand the implications of stress for individual life history strategies. Furthermore, the concept of individual variation in stress tolerance has implications for the immunocompetence handicap hypothesis and the evolution of secondary sexual signals.

Broadband access using wireless-over-fibre technologies

C Liu — 2008-05-07T17:55:22-00:00

BT Technology Journal, Vol. 24, No. 3. (30 July 2006), pp. 130-143.

Abstract This paper describes a number of wireless-over-fibre technologies for broadband access which are being investigated in the Photonics Group at University College London (UCL). In particular, the paper will report the asymmetric Fabry-Perot modulator/detector (AFPM), functioning not only as an optical modulator in the uplink direction, but also as a conventional photodetector in the downlink direction in a single device. Compared to the existing waveguide type electro-absorption modulator, the AFPM is polarisation-insensitive to light, simpler to fabricate and uses only a single optical fibre for both uplink and downlink transmissions, and therefore has the potential to lower the costs of future picocell deployments. Direct modulation of a semiconductor laser is the simplest way to generate modulated optical signals. In the presence of multiple large modulation signals, however, intermodulation or inter-channel distortion can easily be generated in the semiconductor laser and affect other lower power neighbouring channels. A feed-forward linearisation technique for directly modulated semiconductor lasers, capable of operating at frequencies above 5 GHz, has been developed and will be described in detail in this paper. Most modern commercial buildings already have a multimode optical fibre (MMF) infrastructure for carrying the Ethernet data. To provide cost-effective and reliable indoor cellular and wireless local area network (WLAN) coverage without dependence on the radio penetration from outside base-stations, it is highly desirable that the same MMF infrastructure be used to carry these additional services between the equipment room and the remote antenna units around the building. Although not previously regarded as having sufficient bandwidth, it has now been shown that MMF can successfully carry microwave modulated optical signals, including GSM1800 and UMTS cellular radio. Use of MMF for multiservice, multioperator in-building radio coverage has been demonstrated in a collaboration between UCL and the University of Cambridge and will be described in this paper. As the number of cellular and broadband WLAN devices increases, the lower parts of the radio spectrum are becoming more and more congested. To meet the demand for ever higher data transmission rates, other parts of the radio spectrum are being considered for these applications, particularly the millimetre-wave region (30 GHz and above). One of the challenges facing such systems is the generation and delivery of a low phase noise precisely synchronised local oscillator signal. In this paper, a simple optical heterodyne source with two injection locked slave lasers and a more environmentally robust source using an optical injection phase lock loop will be described, together with signal distribution using a bidirectional semiconductor optical amplifier in a coarse wavelength division multiplex fibre ring architecture. Finally it will be argued in the conclusions that future broadband wireless-over-fibre access networks will be required to provide multiservice and multi-operator coverage for buildings, and having the required technologies at sufficiently low cost will be the key factor to success.

Computer access for individuals with quadriplegia.

CW Britell — 2005-08-06T13:57:44-00:00

J Am Paraplegia Soc, Vol. 14, No. 4. (October 1991)

Usability and the bottom line

GM Donahue — 2007-07-30T10:03:48-00:00

Software, IEEE, Vol. 18, No. 1. (2001), pp. 31-37.

There is little debate that usability engineering benefits end users, but its benefit for companies and the people who work for them is less widely known. The author discusses these broader usability benefits and also how to use a cost-benefit analysis to demonstrate the value of usability to your company's bottom line

Cost of an informatics-based diabetes management program.

BB Blanchfield — 2006-07-19T17:09:55-00:00

Int J Technol Assess Health Care, Vol. 22, No. 2. (2006), pp. 249-254.

OBJECTIVES: The relatively high cost of information technology systems may be a barrier to hospitals thinking of adopting this technology. The experiences of early adopters may facilitate decision making for hospitals less able to risk their limited resources. This study identifies the costs to design, develop, implement, and operate an innovative informatics-based registry and disease management system (POPMAN) to manage type 2 diabetes in a primary care setting. METHODS: The various cost components of POPMAN were systematically identified and collected.Results: POPMAN cost 450,000 dollars to develop and operate over 3.5 years (1999-2003). Approximately 250,000 dollars of these costs are one-time expenditures or sunk costs. Annual operating costs are expected to range from 90,000 dollars to 110,000 dollars translating to approximately 90 dollars per patient for a 1,200 patient registry. CONCLUSIONS: The cost of POPMAN is comparable to the costs of other quality-improving interventions for patients with diabetes. Modifications to POPMAN for adaptation to other chronic diseases or to interface with new electronic medical record systems will require additional investment but should not be as high as initial development costs. POPMAN provides a means of tracking progress against negotiated quality targets, allowing hospitals to negotiate pay for performance incentives with insurers that may exceed the annual operating cost of POPMAN. As a result, the quality of care of patients with diabetes through use of POPMAN could be improved at a minimal net cost to hospitals.

The cost of information technology-enabled diabetes management.

J Adler-Milstein — 2007-08-09T18:57:44-00:00

Dis Manag, Vol. 10, No. 3. (June 2007), pp. 115-128.

As a result of the high cost of diabetes, an array of interventions for managing this disease has been developed. Estimating the cost of various approaches to diabetes disease management is critical to inform purchasing decisions. This review focuses on 5 provider- and payer-sponsored diabetes management approaches that use information technology (IT) and provides cost estimates for each approach based on a literature review and interviews with 38 provider practices, hospitals, payers, and vendors. Cost estimates are reported for "typical" small, medium, and large provider practices and payers. Provider-sponsored diabetes registries are estimated to be the least expensive approach for small and medium sized practices. For large practices with electronic health record systems, modifying such systems with diabetes-specific clinical decision support capabilities is projected to be the most economical approach. While limited data prevented the inclusion of all implementation costs, these projections serve as a starting point to inform the purchasing decisions of organizations planning to introduce IT-enabled diabetes management.

Confirmation of a heart failure epidemic: findings from the Resource Utilization Among Congestive Heart Failure (REACH) study

Peter Mccullough — 2007-12-14T05:03:56-00:00

J Am Coll Cardiol, Vol. 39, No. 1. (2 January 2002), pp. 60-69.

OBJECTIVES: The purpose of this study was to create an automated surveillance tool for reporting the incidence, prevalence and processes of care for patients with heart failure. BACKGROUND: Previous epidemiologic studies suggest that the increasing prevalence of heart failure is a consequence of improved survival coupled with minimal changes in disease prevention. Developing new, efficient methods of assessing the incidence and prevalence of heart failure could allow continued surveillance of these rates during an era of rapidly changing treatments and health care delivery patterns. METHODS: Using administrative data sets, we created a definition of heart failure using diagnosis codes. After adjustment for patients leaving our health system or death, we derived the incidence, prevalence and mortality of the population with heart failure from 1989 to 1999. RESULTS: A total of 29,686 patients of all ages, 52.6% women and 47.4% men, met the definition of heart failure. Mean ages were 71.1 +/- 14.5 for women and 67.7 +/- 14.4 for men, p < 0.0001. Race proportions were 50.5% white, 44.6% African American and 4.9% other race. Incidence rates were higher in men and African Americans across all age groups. There was an annual increase in prevalence of 1/1,000 for women and 0.9/1,000 for men, p = 0.001 for both trends. CONCLUSIONS: Through the feasible and valid use of automated data, we have confirmed a chronic disease epidemic of heart failure manifested primarily by an increase in prevalence over the past decade. Our surveillance system mirrors the results of epidemiologic studies and may be a valid method for monitoring the impact of prevention and treatment programs.

Does diabetes disease management save money and improve outcomes? A report of simultaneous short-term savings and quality improvement associated with a health maintenance organization-sponsored disease management program among patients fulfilling health employer data and information set criteria.

J Sidorov — 2006-07-19T18:41:07-00:00

Diabetes Care, Vol. 25, No. 4. (April 2002), pp. 684-689.

OBJECTIVE: Little is known about the impact of disease management programs on medical costs for patients with diabetes. This study compared health care costs for patients who fulfilled health employer data and information set (HEDIS) criteria for diabetes and were in a health maintenance organization (HMO)-sponsored disease management program with costs for those not in disease management. RESEARCH DESIGN AND METHODS: We retrospectively examined paid health care claims and other measures of health care use over 2 years among 6,799 continuously enrolled Geisinger Health Plan patients who fulfilled HEDIS criteria for diabetes. Two groups were compared: those who were enrolled in an opt-in disease management program and those who were not enrolled. We also compared HEDIS data on HbA(1c) testing, percent not in control, lipid testing, diabetic eye screening, and kidney disease screening. All HEDIS measures were based on a hybrid method of claims and chart audits, except for percent not in control, which was based on chart audits only. RESULTS: Of 6,799 patients fulfilling HEDIS criteria for the diagnosis of diabetes, 3,118 (45.9%) patients were enrolled in a disease management program (program), and 3,681 (54.1%) were not enrolled (nonprogram). Both groups had similar male-to-female ratios, and the program patients were 1.4 years younger than the nonprogram patients. Per member per month paid claims averaged 394.62 dollars for program patients compared with 502.48 dollars for nonprogram patients (P < 0.05). This difference was accompanied by lower inpatient health care use in program patients (mean of 0.12 admissions per patient per year and 0.56 inpatient days per patient per year) than in nonprogram patients (0.16 and 0.98, P < 0.05 for both measures). Program patients experienced fewer emergency room visits (0.49 per member per year) than nonprogram patients (0.56) but had a higher number of primary care visits (8.36 vs. 7.78, P < 0.05 for both measures). Except for emergency room visits, these differences remained statistically significant after controlling for age, sex, HMO enrollment duration, presence of a pharmacy benefit, and insurance type. Program patients also achieved higher HEDIS scores for HbA(1c) testing as well as for lipid, eye, and kidney screenings (96.6, 91.1, 79.1, and 68.5% among program patients versus 83.8, 77.6, 64.9, and 39.3% among nonprogram patients, P < 0.05 for all measures). Among 1,074 patients with HbA(1c) levels measured in a HEDIS chart audit, 35 of 526 (6.7%) program patients had a level >9.5%, as compared with 79 of 548 (14.4%) nonprogram patients. CONCLUSIONS: In this HMO, an opt-in disease management program appeared to be associated with a significant reduction in health care costs and other measures of health care use. There was also a simultaneous improvement in HEDIS measures of quality care. These data suggest that disease management may result in savings for sponsored managed care organizations and that improvements in HEDIS measures are not necessarily associated with increased medical costs.

Predictors of health care costs in adults with diabetes.

TP Gilmer — 2006-07-19T18:37:56-00:00

Diabetes Care, Vol. 28, No. 1. (January 2005), pp. 59-64.

OBJECTIVE: The purpose of this study was to assess the impact of baseline A1c, cardiovascular disease, and depression on subsequent health care costs among adults with diabetes. RESEARCH DESIGN AND METHODS: A prospective analysis was performed of data from a patient survey and medical record review merged with 3 years of medical claims. Costs were estimated using detailed data on resource use and Medicare payment methodologies. Generalized linear models were used to analyze costs related to clinical predictors after adjusting for demographic and socioeconomic factors. RESULTS: In multivariate analysis of 1,694 adults with diabetes, 3-year costs in those with coronary heart disease (CHD) and hypertension were over 300% of those with diabetes only (46,879 dollars vs. 14,233 dollars; P < 0.05). Depression was associated with a 50% increase in costs (31,967 dollars vs. 21,609 dollars; P < 0.05). Relative to those with a baseline A1c of 6%, those with an A1c of 10% had 3-year costs that were 11% higher (26,408 dollars vs. 23,873 dollars; P < 0.05). Higher A1c predicted higher costs only for those with baseline A1c >7.5% (P = 0.015). CONCLUSIONS: In adults with diabetes, CHD, hypertension, and depression spectrum disorders more strongly predicted future costs than the A1c level. Concurrent with aggressive efforts to control glucose, greater efforts to prevent or control CHD, hypertension, and depression are necessary to control health care costs in adults with diabetes.

Impact of office systems and improvement strategies on costs of care for adults with diabetes.

TP Gilmer — 2006-07-19T18:29:48-00:00

Diabetes Care, Vol. 29, No. 6. (June 2006), pp. 1242-1248.

OBJECTIVE: To assess the impact of organizational features and improvement strategies of primary care clinics on health care costs of adults with diabetes. RESEARCH DESIGN AND METHODS: This study included a prospective cohort study of 1,628 adults with diabetes in a large, health care organization receiving care in 84 clinics within 18 medical groups. Data from surveys of patients, clinic medical directors and managers, and medical record reviews were merged with 3 years of medical claims. Costs were estimated using health plan data on resource use and common Medicare payment methodologies. Generalized linear regression models were used to analyze costs related to clinic characteristics, adjusting for individual patient comorbidity, demographic, and socioeconomic factors. RESULTS: Clinics with regular clinician meetings to discuss patient care problems and clinics that used diabetes registries to prioritize patients based on cardiovascular risk were associated with lower 3-year costs: -$3,962 (P = 0.002) and -$2,916 (P = 0.019), respectively. The use of databases to monitor lab results was associated with higher costs ($2,439, P = 0.038). Quality improvement strategies focused on resource use related to diabetes care (-$2,883, P = 0.017) or heart disease care (-$3,228, P = 0.014) were associated with lowered costs, whereas quality improvement strategies that emphasized pharmacy use for patients with heart disease ($3,059, P = 0.029) or depression ($2,962, P = 0.038) were associated with increased costs. CONCLUSIONS: Several organizational features of primary care offices were significant predictors of future health care costs for adults with diabetes. The mechanism by which such factors affect costs of care and the relationship of costs to clinical outcomes merits further evaluation.

Rule writing or annotation: cost-efficient resource usage for base noun phrase chunking

Grace Ngai — 2007-10-04T17:13:03-00:00

(2000), pp. 117-125.

Do we listen to advice just because we paid for it? The impact of advice cost on its use

Francesca Gino — 2008-06-16T09:55:55-00:00

Organizational Behavior and Human Decision Processes, Vol. In Press, Corrected Proof

When facing a decision, people often rely on advice received from others. Previous studies have shown that people tend to discount others' opinions. Yet, such discounting varies according to several factors. This paper isolates one of these factors: the cost of advice. Specifically, three experiments investigate whether the cost of advice, independent of its quality, affects how people use advice. The studies use the Judge-Advisor System (JAS) to investigate whether people value advice from others more when it costs money than when it is free, and examine the psychological processes that could account for this effect. The results show that people use paid advice significantly more than free advice and suggest that this effect is due to the same forces that have been documented in the literature to explain the sunk costs fallacy. Implications for circumstances under which people value others' opinions are discussed.

The Nature of the Firm

RH Coase — 2005-05-02T09:05:08-00:00

Suboptimal tradeoffs in information seeking

Wai-Tat Fu — 2005-12-16T19:33:26-00:00

Cognitive Psychology, Vol. In Press, Corrected Proof

Explicit information-seeking actions are needed to evaluate alternative actions in problem-solving tasks. Information-seeking costs are often traded off against the utility of information. We present three experiments that show how subjects adapt to the cost and information structures of environments in a map-navigation task. We found that subjects often stabilize at suboptimal levels of performance. A Bayesian satisficing model (BSM) is proposed and implemented in the ACT-R architecture to predict information-seeking behavior. The BSM uses a local decision rule and a global Bayesian learning mechanism to decide when to stop seeking information. The model matched the human data well, suggesting that adaptation to cost and information structures can be achieved by a simple local decision rule. The local decision rule, however, often limits exploration of the environment and leads to suboptimal performance. We propose that suboptimal performance is an emergent property of the dynamic interactions between cognition and the environment.

Cost-benefit optimization and risk acceptability for existing, aging but maintained structures

H Streicher — 2008-06-19T17:45:54-00:00

Structural Safety, Vol. 30, No. 5. (September 2008), pp. 375-393.

The theory for setting up suitable objective functions is extended to existing structures which can have a different distribution of the time to first failure than all other failure time distributions if systematic reconstruction is chosen in a model based on renewal theory. If components are aging, inspection and maintenance should be performed requiring appropriate modifications. These modifications not only affect the objective function but also the risk function and the failure rate that usually is increasing. Therefore, special consideration is given to the question of risk acceptability where the transient behavior of the failure rate is of interest.

Discounting and the social cost of carbon: a closer look at uncertainty

Jiehan Guo — 2006-03-29T07:04:14-00:00

Environmental Science & Policy, Vol. 9, No. 3. (May 2006), pp. 205-216.

Recently, in the economics literature, several papers have put forward arguments for using a declining discount rate in social-cost benefit analysis. This paper examines the impact of employing a declining discount rate on the social cost of carbon--the marginal social damage from a ton of emitted carbon. Six declining discounting schemes are implemented in the FUND 2.8 integrated assessment model, including the recent amendments to the Green Book of HM Treasury (Treasury, H.M., 2003. The Greenbook: Appraisal and Evaluation in Central Government. TSO, London). We find that using a declining schedule of discount rates increases the social cost of carbon estimate by as little as 10% or by as much as a factor of 40, depending upon the scenario selected. Although the range of plausible estimates is large, using declining discounting schemes in FUND 2.8 in most cases does not yield values at the [UK pound]70/tC level suggested by UK DEFRA [Clarkson, R., Deyes, K., 2002. Estimating the social cost of carbon emissions. Government Economic Service Working Paper. HM Treasury, London]. Indeed, only at the higher end of the values of social cost of carbon found here would many climate change related policies - such as the Kyoto Protocol - pass a cost-benefit analysis. This conclusion, however, does not necessarily undermine the ethical and political economic reasons for supporting international collective action on climate change.

Rate-based query optimization for streaming information sources

Stratis Viglas — 2005-08-02T22:57:13-00:00

(2002), pp. 37-48.

Selectivity estimation for spatio-temporal queries to moving objects

Yong-Jin Choi — 2005-07-05T21:53:28-00:00

(2002), pp. 440-451.

Reliability and cost optimization in distributed computing systems

Chung-Chi Hsieh — 2005-07-03T02:16:34-00:00

Comput. Oper. Res., Vol. 30, No. 8. (July 2003), pp. 1103-1119.

Health care costs of adults treated for attention-deficit/hyperactivity disorder who received alternative drug therapies

EQ Wu — 2008-01-04T21:18:02-00:00

Journal of Managed Care Pharmacy, Vol. 13, No. 7. (September 2007), pp. 561-569.

BACKGROUND: Many therapies exist for treating adult attention-deficit/hyperactivity disorder (ADHD), also referred to as attention-deficit disorder (ADD), but there is no research regarding cost differences associated with initiating alternative ADD/ADHD drug therapies in adults. OBJECTIVE: To compare from the perspective of a large self-insured employer the risk-adjusted direct health care costs associated with 3 alternative drug therapies for ADD in newly treated patients: extended-release methylphenidate (osmotic release oral system-MPH), mixed amphetamine salts extended release (MAS-XR), or atomoxetine. METHODS: We analyzed data from a US claims database of 5 million beneficiaries from 31 large self-insured employers (1999-2004). Analysis was restricted to adults aged 18 to 64 years with at least 1 diagnosis of ADD/ADHD (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes 314.0x--attention deficit disorder; 314.00--attention deficit disorder without hyperactivity; or 314.01--attention-deficit disorder with hyperactivity) and at least 1 pharmacy claim for OROS-MPH, MAS-XR, or atomoxetine identified using National Drug Codes. In preliminary analysis, we calculated the duration of index ADHD drug therapy as time from index therapy initiation to a minimum 60-day gap. Because the median duration of index ADHD drug therapy was found to be approximately 90 days, the primary measures were total direct medical plus drug costs and medical-only costs computed over 6 months following therapy initiation. Adults were required to have continuous eligibility 6 months before and 6 months after their latest drug therapy initiation and no ADHD therapy during the previous 6 months. Cost was measured as the payment amount made by the health plan to the provider rather than billed charges, and it excluded patient copayments and deductibles. Medical costs included costs incurred for all-cause inpatient and outpatient/other services. Costs were adjusted for inflation to 2004 U.S. dollars using the consumer price index for medical care. T tests were used for descriptive cost comparisons. Generalized linear models (GLMs) were used to compare costs of adults receiving alternative therapies, adjusting for demographic characteristics, substance abuse, depression, and the Charlson Comorbidity Index. RESULTS: Of the 4,569 patients who received 1 of these 3 drug therapies for ADHD, 31.8% received OROS-MPH for a median duration of 99 days of therapy, 34.0% received MAS-XR for a median 128 days, and 34.2% received atomoxetine for a median 86 days. In the 6-month follow-up period, the mean (standard deviation) total medical and drug costs were $2,008 ($3,231) for OROS-MPH, $2,169 ($4,828) for MAS-XR, and $2,540 ($4,269) for atomoxetine-treated adults. The GLM for patient characteristics suggested that 6-month, risk-adjusted mean medical costs, excluding drug costs, for adults treated with OROS-MPH were $142 less (10.4%, $1,220 vs. $1,362) compared with MAS-XR (P =0.022) and $132 less (9.8%, $1,220 vs. $1,352) compared with atomoxetine (P =0.033); risk-adjusted mean medical costs were not significantly different between MAS-XR and atomoxetine. The GLM comparison of risk-adjusted total direct costs, including drug cost, was on average $156 less (8.0%, $1,782 vs. $1,938) for OROS-MPH compared with MAS-XR (P = 0.017) and $226 less (11.3%, $1,782 vs. $2,008) compared with atomoxetine (P <0.001); the risk-adjusted total direct costs were not significantly different between MAS-XR and atomoxetine. Two high-cost outliers (greater than 99.96th percentile, 1 each for OROS-MPH and atomoxetine) accounted for $47 (30%) of the $156 cost difference between OROS-MPH and MAS-XR and $11 (5%) of the $226 cost difference between OROS-MPH and atomoxetine, and the medical diagnoses for the highest-cost claims for these 2 outlier patients were unrelated to ADHD. CONCLUSIONS: After adjusting for patient characteristics including substance abuse, depression, and the Charlson Comorbidity Index, adults treated with OROS-MPH had, on average, slightly lower medical and total medical and drug costs than those treated with MAS-XR or atomoxetine over the 6-month period after drug therapy initiation. Approximately 30% of the cost difference compared with MAS-XR was attributable to 1 high-cost outlier with medical diagnoses for the highest-cost claim that were unrelated to ADHD.

Cooperative control of multi-vehicle systems using cost graphs and optimization

RO Saber — 2008-02-22T00:59:46-00:00

American Control Conference, 2003. Proceedings of the 2003, Vol. 3 (2003), pp. 2217-2222 vol.3.

We introduce a class of triangulated graphs for algebraic representation of formations that allows one to specify a mission cost for a group of vehicles. This representation plus the navigational information allows one to formally specify and solve tracking problems for groups of vehicles in formations using an optimization-based approach. The approach is illustrated using a collection of six underactuated vehicles that track a desired trajectory in formation.

Efficient Cost Models for Spatial Queries Using R-Trees

Yannis Theodoridis — 2007-02-03T18:38:11-00:00

Knowledge and Data Engineering, Vol. 12, No. 1. (2000), pp. 19-32.

: Selection and join queries are the fundamental operations in Data Base Management Systems (DBMS). Support for non-traditional data, including spatial objects, in an efficient manner is a new direction in database research. Towards this goal, (a) spatial data structures and access methods, and (b) cost models for spatial queries are necessary tools for spatial query processors and optimizers. In this paper, we present analytical models that estimate the cost (in terms of node or disk accesses) ...

A roadmap of financial measures for IT project ROI

JN Morgan — 2007-10-27T21:02:25-00:00

IT Professional, Vol. 7, No. 1. (2005), pp. 52-57.

Organizations have spent billions of dollars in implementing and subsequently repairing, removing, or altering enterprise-wide IT systems for managing finances, customer relationships, human resources, manufacturing resources, and supply chains. Of all IT systems, those for enterprise resource planning (ERP) are among the most difficult to implement. These products provide turnkey automated processes while sharing common data across an organization. Unsuccessful or grossly underestimated efforts to implement ERP tools have resulted in massive financial failures and corporate process disarray for many organizations. Various financial techniques can help organizations select the right projects and better manage the implementation of enterprise systems. The roadmap describes key practices in the fields of financial management and quantitative analysis.

A cost-oriented methodology for the design of web based IT architectures

Danilo Ardagna — 2007-10-27T21:00:01-00:00

(2002), pp. 1127-1133.

Validation methods for calibrating software effort models

Tim Menzies — 2005-10-10T19:06:15-00:00

(2005), pp. 587-595.

Estimating software project effort using analogies

M Shepperd — 2005-10-10T19:02:13-00:00

Software Engineering, IEEE Transactions on, Vol. 23, No. 11. (1997), pp. 736-743.

Accurate project effort prediction is an important goal for the software engineering community. To date most work has focused upon building algorithmic models of effort, for example COCOMO. These can be calibrated to local environments. We describe an alternative approach to estimation based upon the use of analogies. The underlying principle is to characterize projects in terms of features (for example, the number of interfaces, the development method or the size of the functional requirements document). Completed projects are stored and then the problem becomes one of finding the most similar projects to the one for which a prediction is required. Similarity is defined as Euclidean distance in n-dimensional space where n is the number of project features. Each dimension is standardized so all dimensions have equal weight. The known effort values of the nearest neighbors to the new project are then used as the basis for the prediction. The process is automated using a PC-based tool known as ANGEL. The method is validated on nine different industrial datasets (a total of 275 projects) and in all cases analogy outperforms algorithmic models based upon stepwise regression. From this work we argue that estimation by analogy is a viable technique that, at the very least, can be used by project managers to complement current estimation techniques

Markets and Hierarchies: Some Elementary Considerations

Oliver Williamson — 2007-06-25T23:10:46-00:00

The American Economic Review, Vol. 63, No. 2. (1973), pp. 316-325.

Hierarchical Control and Optimum Firm Size

Oliver Williamson — 2007-06-25T23:09:40-00:00

The Journal of Political Economy, Vol. 75, No. 2. (1967), pp. 123-138.

There is a great deal of evidence that almost all organizational structures tend to produce false images in the decision-maker, and that the larger and more authoritarian the organization, the better the chance that its top decision-makers will be operating in purely imaginary worlds. This perhaps is the most fundamental reason for supposing that there are ultimately diminishing returns to scale.

A personalized approach to analyzing `cost' and `benefit' in vocabulary selection

David Barker — 2008-03-13T06:57:13-00:00

System, Vol. 35, No. 4. (December 2007), pp. 523-533.

The question of which words students should learn and in what order has traditionally been regarded as a matter for teachers and materials writers rather than the learners themselves. Research has focused on using word-specific criteria such as frequency and range of meaning to help teachers make choices about what items to teach to which students at various levels of study. This article suggests that an over-reliance on such an approach fails to prepare learners for the unstructured vocabulary input that they will inevitably have to deal with in the course of their studies. As an alternative, a framework is proposed for taking learners through the process of analyzing new vocabulary items as they meet them. It is suggested that effective training will enable language learners to make their own decisions about the costs and benefits of learning new words based on a consideration of both word- and learner-specific factors.

A Framework for Financial Benefit-Cost Analysis of Individual Development Accounts at the Experimental Site of the American Dream Demonstration

S Mark — 2008-01-17T01:08:32-00:00

The American Dream Demonstration is an evaluation of whether Individual Development Accounts are likely to achieve their intended purposes cost-effectively. Financial benefit-cost analysis is a key input into this overall evaluation. The framework here describes how to estimate the present value of changes in resource flows caused by IDAs for seven groups of stakeholders: IDA participants, non-participants, the federal government, state and local government, employees of IDA programs, private...

Learning and making decisions when costs and probabilities are both unknown

Bianca Zadrozny — 2008-05-14T06:44:32-00:00

(2001), pp. 204-213.

In many data mining domains, misclassification costs are different for different examples, in the same way that class membership probabilities are example-dependent. In these domains, both costs and probabilities are unknown for test examples, so both cost estimators and probability estimators must be learned. After discussing how to make optimal decisions given cost and probability estimates, we present decision tree and naive Bayesian learning methods for obtaining well-calibrated probability ...

Benefit Maximizing Classification Using Feature Intervals

Nazli Ikizler — 2008-05-02T02:58:37-00:00

(September 2002)

For a long time, classification algorithms have focused on minimizing the quantity of prediction errors by assuming that each possible error has identical consequences. However, in many real-world situations, this assumption is not convenient. For instance, in a medical diagnosis domain, misdiagnosing a sick patient as healthy is much more serious than its opposite. For this reason, there is a great need for new classification methods that can handle asymmetric cost and benefit constraints of...

The Foundations of Cost-Sensitive Learning

Charles Elkan — 2008-01-21T08:50:44-00:00

(2001), pp. 973-978.

This paper revisits the problem of optimal learning and decision-making when different misclassification errors incur different penalties. We characterize precisely but intuitively when a cost matrix is reasonable, and we show how to avoid the mistake of defining a cost matrix that is economically incoherent. For the two-class case, we prove a theorem that shows how to change the proportion of negative examples in a training set in order to make optimal cost-sensitive classification decisions...

Skewness of Returns, Capital Adequacy, and Mortgage Lending

Paraskevi Dimou — 2005-11-23T14:01:27-00:00

Journal of Financial Services Research, Vol. 28, No. 1-3. (October 2005), pp. 135-161.

We calibrate a simulation model of credit value-at-risk for mortgage lending to UK experience. Simulations to capture the skewness of returns that might arise in the context of a financial crisis suggest that the IRB calculations of the new Basel Accord can substantially understate prudential capital adequacy. The same model shows that raising capital requirements has only a small impact on bank funding costs. We conclude that Pillar 2 supervisory review should increase capital requirements above IRB levels for secured bank assets—those whose returns can potentially fall furthest, relative to other, normally “riskier” assets, in extreme outcomes.

On measuring the hospital cost/quality trade-off.

K Carey — 2007-03-11T14:09:36-00:00

Health Econ, Vol. 8, No. 6. (September 1999), pp. 509-520.

This paper explores the relationship between cost and quality of hospital care. A total operating cost function is estimated for 137 US Department of Veterans Affairs hospitals for 1988-1993 using three rate-based measures of quality as regressors. The high likelihood of the existence of measurement error in quality in the cross section leads to the application of novel instrumental variable techniques. Results suggest that mortality and readmission indices are adjusted inadequately for illness severity. The measure on the failure to follow up inpatient discharges with outpatient care, however, appears to increase cost. The results of this paper underscore a number of practical difficulties and challenges facing government or other systems in evaluating the relative performance of their hospitals.

The Relationship Between Quality of Care and Costs in Nursing Homes

Robert Weech-Maldonado — 2007-03-11T13:50:58-00:00

American Journal of Medical Quality, Vol. 21, No. 1. (1 January 2006), pp. 40-48.

The purpose of this study was to evaluate the impact of quality of care on costs in nursing homes. The sample consisted of 749 nursing homes in 5 states in 1996. Nursing home cost functionswere estimated using weighted 2-stage least-squares regression analysis. Costs are measured as the facility's total patient care costs. Two outcome measures are used as quality indicators: pressure ulcers worsening and mood decline. Nonmonotonic relationships are observed between quality and costs for nursing homes in the sample. However, the pattern of the relationship is different depending onthe quality indicator. For pressure ulcers, the authors observe an inverted U-shaped curvewith increasing costs at the lower range of quality but decreasing costs associated with higher quality after a threshold. The opposite pattern is observed for mood decline, with a relatively flat curve at the lower range of quality but increasing costs after a threshold. 10.1177/1062860605280643

The trade-off between hospital cost and quality of care. An exploratory empirical analysis.

RC Morey — 2007-03-29T11:25:59-00:00

Med Care, Vol. 30, No. 8. (August 1992), pp. 677-698.

The debate concerning quality of care in hospitals, its "value" and affordability, is increasingly of concern to providers, consumers, and purchasers in the United States and elsewhere. We undertook an exploratory study to estimate the impact on hospital-wide costs if quality-of-care levels were varied. To do so, we obtained costs and service output data regarding 300 U.S. hospitals, representing approximately a 5% cross section of all hospitals operating in 1983; both inpatient and outpatient services were included. The quality-of-care measure used for the exploratory analysis was the ratio of actual deaths in the hospital for the year in question to the forecasted number of deaths for the hospital; the hospital mortality forecaster had earlier (and elsewhere) been built from analyses of 6 million discharge abstracts, and took into account each hospital's actual individual admissions, including key patient descriptors for each admission. Such adjusted death rates have increasingly been used as potential indicators of quality, with recent research lending support for the viability of that linkage. The authors then utilized the economic construct of allocative efficiency relying on "best practices" concepts and peer groupings, built using the "envelopment" philosophy of Data Envelopment Analysis and Pareto efficiency. These analytical techniques estimated the efficiently delivered costs required to meet prespecified levels of quality of care. The marginal additional cost per each death deferred in 1983 was estimated to be approximately $29,000 (in 1990 dollars) for the average efficient hospital. Also, over a feasible range, a 1% increase in the level of quality of care delivered was estimated to increase hospital cost by an average of 1.34%. This estimated elasticity of quality on cost also increased with the number of beds in the hospital.

The sources of hospital cost variability.

B Dormont — 2008-03-12T14:04:18-00:00

Health Econ, Vol. 13, No. 10. (October 2004), pp. 927-939.

Hospital heterogeneity is a major issue in defining a reimbursement system. If hospitals are heterogeneous, it is difficult to distinguish which part of the differences in costs is due to cost containment efforts and which part cannot be reduced, because it is due to other unobserved sources of hospital heterogeneity. In this paper, we apply an econometric approach to analyse hospital cost variability. We use a nested three-dimensional database (stays-hospitals-years) in order to explore the sources of variation in hospital costs, taking into account unobservable components of hospital cost heterogeneity. The three-dimensional structure of our data makes it possible to identify transitory and permanent components of hospital cost heterogeneity. Econometric estimates are performed on a sample of 7314 stays for acute myocardial infarction (AMI) observed in 36 French public hospitals over the period 1994-1997. Transitory unobservable hospital heterogeneity is far from negligible: its estimated standard error is about 50% of the standard error we estimate for cost variability due to permanent unobservable heterogeneity between hospitals.

Omitted variable bias and hospital costs.

PY Crémieux — 2007-08-02T09:40:53-00:00

J Health Econ, Vol. 20, No. 2. (March 2001), pp. 271-282.

This research examines the impact of omitted variables on the accuracy of parametric hospital cost function estimations based on Québec hospital level data. We assess the effect of omitted variables resulting from incomplete data on technology and performance measurement and on tests of the cost minimizing behavior of the institution. Our results show that important characteristics of hospital technology, such as returns to scale, are extremely sensitive to omitted variable bias. Similarly, estimates of hospital performance are poor indicators of actual performance when data are incomplete.

Healthcare payment incentives : a comparative analysis of reforms in taiwan, South Korea and china.

K Eggleston — 2008-04-28T15:10:52-00:00

Applied health economics and health policy, Vol. 3, No. 1. (2004), pp. 47-56.

Payment incentives to both consumers and providers have significant consequences for the equity and efficiency of a healthcare system, and have recently come to the fore in health policy reforms. This review first discusses the economic rationale for the apparent international convergence toward payment systems with mixed demand- and supply-side cost sharing. The recent payment reforms undertaken in Taiwan, South Korea and China are then summarised. Available evidence clearly indicates that payment incentives matter, and, in particular, that supply-side cost sharing can improve efficiency without undermining equity. Further study and monitoring of health service quality and risk selection is warranted.

Econometric estimation of country-specific hospital costs.

Taghreed Adam — 2007-03-01T16:11:56-00:00

Cost Eff Resour Alloc, Vol. 1, No. 1. (26 February 2003)

Information on the unit cost of inpatient and outpatient care is an essential element for costing, budgeting and economic-evaluation exercises. Many countries lack reliable estimates, however. WHO has recently undertaken an extensive effort to collect and collate data on the unit cost of hospitals and health centres from as many countries as possible; so far, data have been assembled from 49 countries, for various years during the period 1973-2000. The database covers a total of 2173 country-years of observations. Large gaps remain, however, particularly for developing countries. Although the long-term solution is that all countries perform their own costing studies, the question arises whether it is possible to predict unit costs for different countries in a standardized way for short-term use. The purpose of the work described in this paper, a modelling exercise, was to use the data collected across countries to predict unit costs in countries for which data are not yet available, with the appropriate uncertainty intervals.The model presented here forms part of a series of models used to estimate unit costs for the WHO-CHOICE project. The methods and the results of the model, however, may be used to predict a number of different types of country-specific unit costs, depending on the purpose of the exercise. They may be used, for instance, to estimate the costs per bed-day at different capacity levels; the "hotel" component of cost per bed-day; or unit costs net of particular components such as drugs.In addition to reporting estimates for selected countries, the paper shows that unit costs of hospitals vary within countries, sometimes by an order of magnitude. Basing cost-effectiveness studies or budgeting exercises on the results of a study of a single facility, or even a small group of facilities, is likely to be misleading.

Effects of cost sharing on physician utilization under favourable conditions for supplier-induced demand

Carine Van De Voorde — 2007-05-15T07:30:08-00:00

Health Economics, Vol. 10, No. 5. (2001), pp. 457-471.

The effects of cost sharing on the demand for ambulatory care in experimental circumstances are well understood since the Rand Health Insurance Experiment (HIE). However, in a non-experimental real-world context, supplier-induced demand of doctors might erode some of the significant negative out-of-pocket price elasticity identified in the HIE. Belgium is an interesting test case for this hypothesis because it has relatively high rates of patient cost sharing in its public health insurance system and a very high density of physicians, all remunerated fee-for-service. We have exploited the price variation generated by a substantial increase in patient co-payment rates in 1994 to estimate out-of-pocket price elasticities for three groups of users, and for three types of services using a fixed-effects model in levels and in differences. We obtain significant out-of-pocket price elasticities for the general population in the range from -0.39 to -0.28 for GP home visits, -0.16 to -0.12 for GP office visits and -0.10 for specialist visits. The estimates were generally lower and less significant for the groups of elderly and disabled. The differences we find in price responsiveness appear to be fairly robust and consistent with the HIE predictions. These results suggest that - at least in the short run - non-experimental utilization effects of cost sharing are very similar to the experimental evidence, even in a situation of favourable conditions for supplier-induced demand. Copyright © 2001 John Wiley & Sons, Ltd.

Determinants of variation in the cost of inpatient stays versus outpatient visits in hospitals: a multi-country analysis.

T Adam — 2007-06-25T09:24:35-00:00

Soc Sci Med, Vol. 63, No. 7. (October 2006), pp. 1700-1710.

Information on hospital costs is key to many types of economic and financial analyses, yet many countries lack reliable estimates due partly to the time and resources required to undertake detailed costing studies. Accordingly, some analysts have used simple rules of thumb to estimate hospital unit costs, e.g., total hospital costs are allocated between departments assuming that the cost of an inpatient day equals a fixed number of outpatient visits. This paper first explores the extent to which these simple rules apply within and across countries. It then identifies determinants of variation in the relationship between the cost of outpatient visits and inpatient days, then uses the estimated relationship to calculate average costs of inpatient and outpatient stays for countries where data are not yet available. Cost information from 832 hospitals in 28 countries are used. We show that simple rules of thumb do not prove to be an accurate basis for cost estimates. The ratio of inpatient to outpatient unit costs varies with GDP per capita, hospital size, ownership, and occupancy rate. We show how the estimated relationship can be used to calculate a mean cost of inpatient stays and outpatient visits, taking into account differences in the levels of key determinants, and argue that, in the absence of a representative sample of hospital costing studies, this method can be used to estimate unit costs in the interim. Moreover, we suggest that the observed great variation in unit costs for similar hospitals in the same country means that this method might well be preferable to basing policy advice on the results of costing studies that cover only one, or a few hospitals, which might well be outliers.

Cost efficiency of US hospitals: a stochastic frontier approach.

MD Rosko — 2007-02-13T17:29:41-00:00

Health Econ, Vol. 10, No. 6. (September 2001), pp. 539-551.

This study examined the impact of managed care and other environmental factors on hospital inefficiency in 1631 US hospitals during the period 1990-1996. A panel, stochastic frontier regression model was used to estimate inefficiency parameters and inefficiency scores. The results suggest that mean estimated inefficiency decreased by about 28% during the study period. Inefficiency was negatively associated with health maintenance organization (HMO) penetration and industry concentration. It was positively related with Medicare share and for-profit ownership status.

The market for efficiency analysis of health care organisations.

B Hollingsworth — 2007-02-13T17:29:10-00:00

Health Econ, Vol. 15, No. 10. (October 2006), pp. 1055-1059.

Cost inefficiency and mortality rates in Florida hospitals.

ME Deily — 2007-02-13T17:23:54-00:00

Health Econ, Vol. 15, No. 4. (April 2006), pp. 419-431.

This study examines the relationship between health outcomes and cost inefficiency in Florida hospitals over the period 1999-2001, with health outcomes measured by risk-adjusted in-hospital mortality rates. Previous research has come to conflicting conclusions regarding the relationship between costs and health outcomes. We hypothesize that these seemingly conflicting findings are due to the fact that total cost has two components--cost that reflects the best use of resources under current circumstances and cost associated with waste or inefficiency. By isolating costs due to inefficiency, we can examine directly their relationship, if any, to hospital mortality rates, and begin to assess whether policies that create incentives for hospitals to increase efficiency have adverse effects on health outcomes. We regress an in-hospital mortality index for each hospital on a measure of the hospital's cost inefficiency, obtained from a stochastic cost frontier estimation, as well as on predicted mortality and a set of variables linked to mortality performance. Our results indicate a positive and significant relationship between a hospital's mortality performance and its inefficiency: on average, a one percentage point reduction in cost inefficiency would be associated with one fewer in-hospital death per 10,000 discharges, holding patient risk and other factors constant.

The productivity of health care.

K Bloor — 2007-02-13T17:23:13-00:00

Health Econ, Vol. 15, No. 12. (December 2006), pp. 1257-1259.

Behavioral differences between public and private not-for-profit hospitals in the Italian National Health Service.

GP Barbetta — 2007-02-13T17:08:57-00:00

Health Econ, Vol. 16, No. 1. (January 2007), pp. 75-96.

In this paper we attempt to identify behavioral differences between public and private not-for-profit hospitals, by exploiting the introduction of the DRG-based payment system in the Italian NHS during the second half of the 1990s. We estimate the technical efficiency of a sample of hospitals for the period 1995-2000 considering an output distance function, and adopting both parametric (COLS and SF) and nonparametric (DEA) approaches. Our results show a convergence of mean efficiency scores between not-for-profit and public hospitals, and seem to suggest that differences in economic performances between competing ownership forms are more the result of the institutional settings in which they operate than the effect of the incentive structures embedded in the different proprietary forms. We also observe a decline in technical efficiency, probably due to policies aimed at reducing hospitalization rates.

Accounting for quality in the measurement of hospital performance: evidence from Costa Rica.

Pablo Arocena — 2007-02-13T17:08:36-00:00

Health Econ (19 December 2006)

This paper provides insights into how Costa Rican public hospitals responded to the pressure for increased efficiency and quality introduced by the reforms carried out over the period 1997-2001. To that purpose we compute a generalized output distance function by means of non-parametric mathematical programming to construct a productivity index, which accounts for productivity changes while controlling for quality of care. Our results show an improvement in hospital performance mainly driven by quality increases. The adoption of management contracts seems to have contributed to such enhancement, more notably for small hospitals. Further, productivity growth is primarily due to technical and scale efficiency change rather than technological change. A number of policy implications are drawn from these results. Copyright (c) 2006 John Wiley & Sons, Ltd.

The effect of selective contracting on hospital costs and revenues.

J Zwanziger — 2008-04-25T13:26:34-00:00

Health services research, Vol. 35, No. 4. (October 2000), pp. 849-867.

OBJECTIVE: To examine the effects of selective contracting on California hospital costs and revenues over the 1983-1997 period. DATA SOURCES/STUDY SETTING: Annual disclosure data and discharge data sets for 421 California general acute care hospitals from 1980 to 1997. ANALYSIS: Using measures of competition developed from patient-level discharge data, and financial and utilization measures from the disclosure data, we estimated a fixed effect multivariate regression model of hospital costs and revenues. FINDINGS: We found that hospitals in more competitive areas had a substantially lower rate of increase in both costs and revenues over this extended period of time. For-profit hospitals lowered their costs and revenues after selective contracting was initiated relative to the cost and revenue levels of not-for-profit hospitals. The Medicare PPS has also led high-cost hospitals to lower their costs. CONCLUSIONS: The more competitive the hospital's market, the greater degree to which it has had to lower the rate of increase in costs. A similar pattern exists with regard to hospital revenues. Both of these trends appear to result from the growth of selective contracting. It remains unclear to what extent these cost reductions were the result of increased efficiency or of reduced quality. Since hospital cost growth is sensitive to the competitiveness of its market, antitrust enforcement is a critical element in any cost containment policy.