Separate Decisions Research Articles

Postoperative management of stage II/III colon cancer: A decision analysis

Background & Aims: Two separate decisions must be made for the management of patients with resected stage II/III colon cancer: whether to begin adjuvant chemotherapy and whether patients should be included in a follow-up protocol consisting of regular monitoring of carcinoembryonic antigen level and of colonoscopy and imaging. The standard management for these patients is adjuvant chemotherapy for stage III patients and follow-up for stage II/III patients with resected colon cancer. Methods: Decision analysis was used to compare the effectiveness (5-year survival rate) and cost-effectiveness ratio of 7 strategies of treatment and follow-up. Results: The most cost-effective strategies were adjuvant chemotherapy for all patients with stage II/III resected colon cancer, with either no follow-up or follow-up only for patients aged less than 75 years with a seric preoperative carcinoembryonic antigen level of >5 ng/mL (5-year survival, 62.3% or 62.7%; cost per surviving patient, $8254 or $8657, respectively). The order of efficacy of the strategies was insensitive to changes in the values of the studied variables. The method of follow-up does little to improve 5-year survival but adds substantial cost. Conclusions: The current standard strategy may not be the most cost-effective strategy for the management of patients with resected colon cancer. GASTROENTEROLOGY 1999;117:784-793

Modeling the Conditional Probability of Foreclosure in the Context of Single‐Family Mortgage Default Resolutions

Both empirical and pricing‐simulation models of mortgage default focus on foreclosure in a one‐step decision framework. Such models are misspecified to the extent that mortgage default and foreclosure are two separate decisions or events, where foreclosure is but one outcome of a default episode. This study examines the dynamics of mortgage borrower default episodes using a large sample of FHA‐insured single‐family mortgages. We estimate the influence of borrower characteristics, mortgage terms, and economic conditions on probabilities of various resolutions, highlighting under what conditions foreclosure is more likely to result from mortgage default.

Extensions of "The Tragedy of the Commons"

Extensions of "The Tragedy of the Commons"

New Projects Receive Boost As Cuts Pinch Current Work

TOKYO-- In its efforts to revive its precarious economy, the Japanese government is pouring money into new scientific projects and facilities, while squeezing the operating and maintenance budgets of several major existing programs. This odd situation is the result of two separate budget decisions and a tangle of laws and regulations that restrict how ministry officials and institute administrators can spend appropriated funds. Last week, the government announced a $128 billion package of spending and tax cuts that includes at least $11.5 billion for a host of scientific efforts ranging from new laboratories to high-speed computer networks.

Revision of industrial supply conditions and game theory

We analyze the real case of two firms evaluating a shift from a “risk and revenue sharing agreement” to a supplying agreement. From the point of view of economic theory, this is a constrained bilateral monopoly problem. At the first stage, the two firms take sequential decisions of price and demand, with price being represented not only as a simple level, but also as a more realistic price schedule. In this more general case we solve a variational problem by transforming it — with no restrictions — into a classical mathematical programming one. At the second stage, the two firms are allowed to bargain over a couple price-quantity instead of taking separate decisions about them. As expected, bargaining is efficient with respect to the constant price case. In the price schedule case however efficiency does not hold without further conditions.

Voting Cycles in Business Curriculum Reform, a Note

The theoretical potential for voting cycles is well known, but the empirical frequency of its occurrence is still a topic for research. This paper presents a case study of the occurrence of voting cycles in business school curriculum reform. Three separate decisions are analyzed: (1) addition of a service requirement, (2) additions to the business core, and (3) changes in the nature of majors/“concentrations.” A voting cycle was found in (2) but not (1) or (3). This result is consistent with theoretical analyses finding that cycles are more likely when there are more alternatives to be considered and when there is less similarity in individual preferences.

Using Genetic Algorithms to Optimize the Selection of Cost Drivers in Activity-based Costing

In this paper, we address a cost-drivers optimization (CDO) problem in which two separate but interrelated decisions (i.e. the number of cost drivers needed and which cost drivers to use) are considered. It is desirable to have (1) an optimal selection of cost drivers in order to provide better indication of product costs and (2) an optimal number of cost drivers in order to avoid excessive control costs and to minimize information costs associated with data collection, storage and processing. The objective of the CDO problem is to balance savings in information costs with loss of accuracy. We propose an heuristic procedure based on genetic algorithms as an alternative with the potential to address more generalized objective functions. Genetic algorithms represent an innovative and promising heuristic approach which does produce results superior to published alternatives. The development and implementation of the algorithm is supported with the literature review and comparative analysis. We also comment on the complexity and experimental design issues for addressing large and practical problems. © 1996 Wiley Periodicals, Inc.

ALTERNATIVE APPROACHES TO MODELLING ZERO EXPENDITURE: AN APPLICATION TO SPANISH DEMAND FOR TOBACCO*

AbstractThe purpose of this paper is to emphasise the importance of double‐hurdle models in the estimation of tobacco demand equations. Using data from the Spanish Family Expenditure Survey (EPF), Tobit, P‐Tobit and first hurdle dominance models are shown to be restrictive. This dataset also confirms the existence of separate individual decisions on participation and consumption. We propose to estimate a dependent version of a double‐hurdle model, although independence is not restrictive once additional powers of total expenditure are included in the specification of the second hurdle. Several misspecification tests are also conducted among the different models.

Training the fuzzy integral

The value of the fuzzy integral in a decision making environment where uncertainty is present has been well established. The fusion of multiple information sources is very valuable in overcoming the inherent ambiguities present in single information sources and in resolving conflicting information from separate decisions. However, using the fuzzy integral to overcome such uncertainties introduces an uncertainty of its won, specifically that of generating the importance of each subset of the information sources in determining an unambiguous solution. In this paper, a neuron model for using the fuzzy integral in a multiclass decision making environment us presented. A method of training the fuzzy density values from labeled data is developed. This training algorithm uses a reward and punishment scheme in order to increase the reliability of the decision making process. The result of this training is a set of fuzzy density values which represents the importance of each source with respect to the decision. One important feature of this method is that the fuzzy density values for all classes are considered at each iteration, resulting in more comparable values for the fuzzy integrals, a troublesome problem with many independent training algorithms. The training algorithm is demonstrated with synthetic data and in an automatic target recognition application.

Joint optimization of maintenance and inventory policies for a simple system

We examine age replacement and ordering decisions for a system with only one component subject to random failure and with room for only one spare in stock. The system incurs costs for replacement, shortage, holding, and breakage; the lead time for receipt of an ordered spare is constant. We consider the solvability and desirability of jointly optimizing these two traditionally separate decisions. We show that the problem has some convexity properties that make it amenable to minimization. For our data set, we find that using separate optimization gives an average loss of 3% relative to the joint minimum; about a tenth of die time the difference was more than 10%, but in general this loss can vary from zero to arbitrarily large.

Economic Approaches to Understanding Nonmarital Fertility

This book chapter presents a strategy for modeling nonmarital fertility and marriage as separate decisions by gender. The growth of nonmarital fertility in the US and the differences by race and socioeconomic status are explained in a model by Willis (1995) on the labor market experiences of men and women. Nonmarital childbearing can be explained by the balance between mens ability to take advantage of womens willingness and ability to raise their children and mens low or zero economic costs of child support. The net impact of womens income and price effects could result in having no children or fewer children because the child costs are greater than what she may be willing to pay from her own full income. Public goods theory implies that allocations of joint incomes of both father and mother could increase the utility of both parents. But if the mother cares more than the father about the well-being of the children the greater will be the expenditures particularly from the mother because of free-riding associated with the provision of public goods. An efficient allocation of resources for child support is not expected in a noncooperative bargaining model (a Stackelberg model) between a single custodial mother and a noncustodial father. As the mother increases her income and is able to support the child at a more adequate level from her own resources the fathers optimum transfer of income tends to decrease and even reach zero. Marriage and a binding contract that includes provisions in a potential divorce settlement solves collective goods problems. Weiss and Willis argue that deadbeat dads may withdraw generous support that occurred within marriage when love trust and mutual altruism between husband and wife disappear in divorce. Argys and Peters argument is that cooperative agreements about shared resources are possible among parents not living together but these parents face many difficulties. Policy can directly raise the cost of nonmarital fertility to men.

Voice communication processing system

A voice communication processing system and method for processing a speech waveform as a digital bit stream having a reduced number of bits representing speech parameters. The bit representation of amplitude parameters is reduced by storing only probable amplitude parameter transitions corresponding to amplitude parameter indices in an amplitude table and by joint encoding the amplitude parameter indices over multiple frames. The bit representation of the pitch period is reduced by storing a range of pitch periods in a pitch table and by joint encoding pitch period indices corresponding to an average pitch period over two frames. The bit representation of the vocal tract filter coefficients is reduced by storing only probable filter coefficient transitions corresponding to filter coefficient indices in a filter coefficient table and by joint encoding the filter coefficient indices over two frames. Voicing decisions are inferred by an associated vocal tract filter coefficient index obtained by searching the filter coefficient table where the table is divided according to the voicing decisions, and thus separate voicing decisions do not have to be transmitted. By providing a reduced bit representation of the various speech parameters as explained above, the present invention processes the speech waveform at a more efficient data rate. In addition, the present invention converts prediction coefficients (PCs) into line spectra pairs (LSPs) to be used as filter parameters when performing a linear predictive coder (LPC) analysis. Thus, by using LSPs, the present invention is able to more efficiently encode and decode speech.

Core business regulation and dual diversification patterns in the telecommunications industry

AbstractA firm is confronted with the separate decisions of product and international diversification. It is suggested that these postures are linked to external contingencies in firms who face core business regulation. A technique is developed to explain dual diversification patterns using evidence obtained from the new industry comprised of the Regional Bell Operating Companies (RBOCs).

Theoretical and empirical specification of a model of informal labeling

Recently criminologists have begun to explore the importance of disaggregating frequency measures of self-reported delinquency into the separate decisions of initiation and continuation. Given that labeling makes predictions concerning continuation, the purpose of this paper is twofold. The first is to test the ability of an informal labeling model to predict the decision to continue delinquent behavior once it is initiated. The second purpose is to address the broader question of whether disaggregation matters. The findings support the idea that the informal labeling model is predictive of the decision to continue delinquent behavior. The findings also suggest that, at least for a measure of general delinquency, there are some differences to be found by choosing the appropriate sample and form of the dependent variable.

CONSUMERS‘ DECISIONS WHETHER OR NOT TO PURCHASE MEAT: A DOUBLE HURDLE ANALYSIS OF SINGLE ADULT HOUSEHOLDS

Limited dependent variable models are employed to determine factors influencing UK household meat purchase behaviour. The standard Tobit approach is rejected. “Double hurdle” models, specifically the Cragg and Complete Dominance versions, provide a better representation of the factors that influence the separate decisions of participation and expenditure levels. Key results show that employment class and adult gender are significant determinants of participation but not expenditure; income affects both decisions but in opposite directions; education affects expenditure alone.

Estimating the Choice Behavior of Self-Employed Business Proprietors: An Application to Dairy Farmers

The vast majority of business concerns operating in contemporary market oriented economies are owned and controlled by a single individual and perhaps family members. Yet little work has been performed in the area of estimating the choice behavior of self-employed business proprietors, particularly under conditions where production and consumption decisions are interdependent. Lau, Lin, and Yotopolous [16], Barnum and Squire [2], and others have developed models to analyze and estimate the complete choice behavior of farm households in developing nations. These analyses invariably separate production and consumption decisions so that the sole link between the two sides of the model lies in the impact of farm profit on the household budget constraint. This type of separability implicitly assumes the existence of perfect markets for all goods and inputs.' While this assumption may be a valid approximation for many farm households in developing economies, it is not generally applicable to self-employed proprietors, especially those operating in more advanced economies [8; 19; 21; 26]. To my knowledge, only two prior empirical studies have been performed which attempt to analyze the choice behavior of self-employed business proprietors under conditions where production and consumption decisions are interdependent. Brown and Lapan [4] employ aggregate U.S. time series data to estimate physician labor and output supply responses to changes in output price. Their estimation procedure centers on a single reduced form output supply equation. Parameter estimates are interpreted in the context of the theoretical framework assuming constant returns to scale technology and homothetic preferences. They conclude that while the physician labor supply curve is backward bending, the output supply curve is positively sloped. Lopez [19] formulates a model analyzing the interdependent production and labor supply decisions of households that own and operate a farm. His framework integrates output, input, and labor supply choices, and allows for differences in preferences between on-farm and off-farm work. Imposing constant returns to scale and using cross-section Canadian data aggregated by census division, he jointly estimates output supply, input demand, on-farm, and off-farm labor

The Meat Purchase Decision

Reports on an investigation, using econometric techniques, of the household demand for meat as two separate decisions: whether or not to buy meat, and how much to buy. Based on single adult households in the Family Expenditure Survey, it highlights the importance of age, gender, employment class and education of householder, as well as the presence of children and freezer ownership.

A Prospective Investigation of Racial Disparity in the Juvenile Justice System

Abstract Black males are over‐represented in the juvenile justice system. With the exception of a few recent studies, most investigations to determine why such over‐representation exists have used retrospective data from existing records, conceptualized their research as a series of separate juvenile justice decisions, and employed bivariate and zero‐order correlation techniques. This paper presents the results of a prospective study designed to determine why disproportionately more black than white males are represented in Georgia's juvenile justice system. Youth from eight communities were tracked through four decision points: police apprehension, and juvenile court intake, adjudication, and disposition. The study examines the direct and indirect effects of race on decision making. Multivariate analysis methods allowed specification of results for each separate decision point as well as the cumulative effects of race across decision points.

Dividing attention between color and shape: evidence of coactivation.

When attention is divided between spatially distinct objects, the time to detect a target decreases when two or more targets are present. This redundancy gain can be accounted for by an interactive race model (Mordkoff & Yantis, 1991) in which separate decisions are made about each object, but environmental contingencies among the objects can influence decision times. In the present study, we examined whether the model also accounts for performance when attention must be divided between stimulus attributes other than spatial location. Subjects made target-present responses when displays included a prespecified color, a prespecified letter, or both target features. The data violated the predictions of all separate-activations models, including the interactive race model. Two control experiments ruled out an alternative account based on task complexity. We conclude that coactivation occurs when target attributes from two separable dimensions are simultaneously present, but not when target attributes come from the same dimension. A modular hybrid of race and coactivation models is tentatively proposed.

The case for mandatory municipal disclosure: Do seasoned municipal bond yields impound publicly available information?

The purpose of this study is to examine the adequacy of currently available public information in pricing seasoned municipal bonds. Yield premia for bonds with known changes in credit quality are evaluated, employing a procedure which attempts to separate rating decisions which are predictable, using publicly available information, from those which are not. We find that rating decisions which can be predicted using currently available information are anticipated at least two years in advance of the rating announcement. Rating changes which are not predictable, however, are not anticipated by the market. In addition to providing information on the need for additional disclosure regulation in the municipal bond market, this evidence represents a contribution to the municipal, and possibly corporate, bond literature by demonstrating that the expected information content for all rating announcements is not the same.