Large Number Of Control Variables Research Articles

Staggered boards, accounting discretion and firm value

Motivated by agency theory, this study investigates how staggered boards influence accounting discretion. The results indicate that staggered boards do affect accounting discretion. In fact, the impact of staggered boards on accounting discretion is substantially larger (about seven times stronger) than the effect of all other corporate governance provisions combined. Firms with a staggered board exercise less income inflating accounting discretion. Further evidence reveals that accounting discretion has a benign effect on subsequent firm value. Yet, the presence of staggered boards reduces significantly the favourable effect of accounting discretion on subsequent firm performance. The evidence is robust to a large number of control variables including other governance provisions. The evidence is in line with the notion that staggered boards improve managers’ job security, reduce managerial myopia, and thus induce managers to exercise less short-term transitory accounting discretion.

Intelligence and physical attractiveness

This brief research note aims to estimate the magnitude of the association between general intelligence and physical attractiveness with large nationally representative samples from two nations. In the United Kingdom, attractive children are more intelligent by 12.4 IQ points ( r = .381), whereas in the United States, the correlation between intelligence and physical attractiveness is somewhat smaller ( r = .126). The association between intelligence and physical attractiveness is stronger among men than among women in both nations. The association remains significant net of a large number of control variables for social class, body size, and health.

Staggered Boards, Accounting Discretion, and Firm Value

Motivated by agency theory, this study investigates how staggered boards influence accounting discretion. The results indicate that staggered boards do affect accounting discretion. In fact, the impact of staggered boards on accounting discretion is substantially larger (about seven times stronger) than the effect of all other corporate governance provisions combined. Firms with a staggered board exercise less income-inflating accounting discretion. Further evidence reveals that accounting discretion has a benign effect on subsequent firm value. Yet, the presence of staggered boards reduces significantly the favorable effect of accounting discretion on subsequent firm performance. The evidence is robust to a large number of control variables including other governance provisions. The evidence is in line with the notion that staggered boards improve managers’ job security, reduce managerial myopia, and thus induce managers to exercise less short-term transitory accounting discretion.

Venture Capital Availability and Labor Market Performance in Industrial Countries: Evidence Based on Survey Data

This paper finds that more readily available venture capital is likely to have lowered unemployment rates and raised employment rates in industrial countries over the period 1982 to 2003. More readily available venture capital is also likely to have lowered the share of long-term unemployed in the total number of unemployed. The magnitude of the effects appears to have been substantial. To measure access to venture capital, we use answers from surveys of senior business executives. We also employ a large number of control variables. Our regression results are robust to variations in specification and sample size.

Combined use of dimensional analysis and modern experimental design methodologies in hydrodynamics experiments

In this paper, a combined use of dimensional analysis (DA) and modern statistical design of experiment (DOE) methodologies is proposed for a hydrodynamics experiment where there are a large number of variables. While DA is well-known, DOE is still unfamiliar to most ocean engineers although it has been shown to be useful in many engineering and non-engineering applications. To introduce and illustrate the method, a study concerning the thrust of a propeller is considered. Fourteen variables are involved in the problem and after dimensional analysis this reduces to 11 dimensionless parameters. Then, a two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent dimensionless parameter. With the remaining five statistically significant dimensionless parameters, various response surface methodologies (RSM) were used to obtain a functional relationship between the dependent dimensionless thrust coefficient, and the five dimensionless parameters. The final model was found to be of reasonable accuracy when tested against results not used to develop the model. The methodologies presented in the paper can be similarly applied to systems with a large number of control variables to systematically derive approximate mathematical models to predict the responses of the system economically and accurately.

Evaluation of the parameterization‐simulation‐optimization approach for the control of reservoir systems

Most common methods used in optimal control of reservoir systems require a large number of control variables, which are typically the sequences of releases from all reservoirs and for all time steps of the control period. In contrast, the less widespread parameterization‐simulation‐optimization (PSO) method is a low‐dimensional method. It uses a handful of control variables, which are parameters of a simple rule that is valid through the entire control period and determines the releases from different reservoirs at each time step. The parameterization of the rule is linked to simulation of the reservoir system, which enables the calculation of a performance measure of the system for given parameter values, and nonlinear optimization, which enables determination of the optimal parameter values. To evaluate the PSO method and, particularly, to investigate whether the radical reduction of the number of control variables might lead to inferior solutions or not, we compare it to two alternative methods. These methods, namely, the high‐dimensional perfect foresight method and the simplified “equivalent reservoir” method that merges the reservoir system into a single hypothetical reservoir, determine “benchmark” performance measures for the comparison. The comparison is done both theoretically and by investigation of the results of the PSO against the benchmark methods in a large variety of test problems. Forty‐one test problems for a hypothetical system of two reservoirs are constructed and solved for comparison. These refer to different objectives (maximization of reliable yield, minimization of cost, maximization of energy production), water uses (irrigation, water supply, energy production), characteristics of the reservoir system and hydrological scenarios. The investigation shows that PSO yields solutions that are not inferior to those of the benchmark methods and, simultaneously, it has several theoretical, computational, and practical advantages.

Optimal Power Flow Using Refined Genetic Algorithm

This article presents a simple, effective, and reliable refined genetic algorithm (RGA) for solving the optimal power flow (OPF) problem. This genetic algorithm with the exponential variation of crossover probability, mutation probability, anddynamic hierarchy of the coding system has the ability to code a large number of control variables in a practical system, within a reasonable length of chromosome, and the algorithm is less sensitive to starting points. It is, therefore, able to regulate the active power outputs of generators, bus voltages, shunt capacitors/reactors, and transformer tap-settings to minimize the fuel cost. The feasibility of the algorithm is demonstrated using the IEEE 6-bus and 30-bus systems.

Thermodynamic optimal design of heat exchangers for an irreversible refrigerator

Thermodynamic optimisation of energy systems is essential in reducing the environmental impact of energy utilisation. Yet, the refrigerators commonly used for this purpose have improvable efficiency levels. Their performance, as shown by the literature, is highly influenced by the size of the heat exchangers and by internal irreversibilities. In this paper the maximum coefficient of performance ( COP) is obtained for an irreversible inverse Rankine cycle refrigerator working with the environmentally friendly fluid R134a. This is a steady-state refrigerator working as an open system which consumes external work, subtracts heat from a cold fluid stream at an inlet fixed temperature and assigns it to a higher fixed inlet temperature stream. Heat transfer irreversibilities in the shell-and-tube heat exchangers and external friction losses in the water streams are considered, ignoring only the internal pressure drop of vapor. A simulation program was developed to search the maximum COP at given external fluid temperatures, as a function of mass flows, dimensions and temperature differences in the heat exchangers. Owing to the large number of control variables involved, a numerical optimisation method was used to determine the maximum COP. The proposed method is fast, producing the maximum with acceptable approximation. It provides the refrigerating fluid evaporating and condensing pressures, the heat exchanger dimensions, and the water flow rates for a given cooling power with predefined inlet temperatures of cold and hot water streams. The heat exchanger area closely conditions the COP, so each maximum represents the optimum thermodynamic working conditions for a given area of the heat exchangers.

Sibling mortality correlation in Kenya.

This paper examines whether infant and child mortality risks among successive siblings are closely correlated, and if so, whether the survival status of the preceding child is an important factor affecting infant and child mortality in Kenya. The data were drawn from the 1988/89 Kenya Demographic and Health Survey. Logistic regression was used as the major method of data analysis. The results show that both infant and child mortality rates are significantly higher among subsequent children whose preceding siblings had died in infancy than for those whose preceding sibling had survived through infancy. The effect of the survival status of the preceding child on infant mortality was statistically strong, even after a large number of control variables were taken into account. However, its effect on child mortality appears to be spurious since it was rendered statistically insignificant when just a few control variables were introduced into the analysis. The results provide empirical evidence that infant and child mortality risks among successive siblings are closely correlated in Kenyan families, and that the effect of the survival status of the preceding child is important in determining infant mortality but not child mortality.

Spent nuclear fuel and residential property values: the influence of proximity, visual cues and public information

This article examines whether public knowledge of spent fuel storage at nuclear power plants, and any local adverse risk perceptions that may have occurred, affect the sale price of single-family residential properties. We present evidence from the Rancho Seco, California, plant on residential property values using an hedonic modeling framework. We include a large number of control variables, data with a high level of spatial detail and a number of public information variables in order to model property market effects within a fifteen mile radius of the plant. Our findings indicate that proximity and visual reminders of the plant have some influence on local property markets, and that there is a small media coverage effect on single-family home sale prices.

Spent nuclear fuel and residential property values: the influence of proximity, visual cues and public information

Abstract. This article examines whether public knowledge of spent fuel storage at nuclear power plants, and any local adverse risk perceptions that may have occurred, affect the sale price of single‐family residential properties. We present evidence from the Rancho Seco, California, plant on residential property values using an hedonic modeling framework. We include a large number of control variables, data with a high level of spatial detail and a number of public information variables in order to model property market effects within a fifteen mile radius of the plant. Our findings indicate that proximity and visual reminders of the plant have some influence on local property markets, and that there is a small media coverage effect on single‐family home sale prices.

Improved genetic algorithms for optimal power flow under both normal and contingent operation states

This paper presents an improved genetic algorithm (IGA) to solve the problem of optimal power flow. The GA, with the dynamical hierarchy of the coding system developed in this paper, has the ability to code a large number of control variables in a practical system within a reasonable length string. It is, therefore, able to regulate the active power outputs of generators, bus voltages, shunt capacitors/reactors and transformer tap-settings to minimize the fuel costs. Two cases in the IEEE 30-bus system for both normal and contingent operation states have been studied. In the contingent state, the circuit outage is simulated in one branch which causes a power flow violation in the other branch. The IGA always finds the best results and eliminates operational and insecure violations.

Optimization of Jc of YBCO thin films prepared by photo-assisted MOCVD through statistical robust design

Intrinsically, the thin-film preparation technique of metalorganic chemical vapor deposition involves a large number of control variables which are especially critical in work with quaternary or higher high- T c materials. Thus, effective methods are needed to optimize variable settingsin the preparation of high- T c films. A matrix experimental plan and robust design methodology has been employed for this purpose. The first design phase was based on existing knowledge regarding growth temperature, pressure and annealing temperature for photo-assisted preparation of YBCO thin films on LaAlO 3 (100) substrates. A battery of only nine experiments plus three confirmation depositions were then used to optimize the process control parameters of precursor oven temperature, carrier gas (Ar) flow rate, and the flow rates of two oxidizing gases, O 2 and N 2O, with respect to critical current density ( J c) of the films. J c (77 K, zero field) values for deposited YBCO films (with thickness in the 0.4–0.6 μm range) were found to be improved from about 1 to 3 × 10 6 A/cm 2. J c for a thinner sample (0.15 μm) reached 5.0 × 10 6 A/cm 2. It was found that under these processing conditions the most significant process control parameter affecting J c is the flow rate of O 2, or more precisely, the oxidizing agent flow-rate ratio of O 2 and N 2O. Analysis of the variance of the J c data indicated that there likely exist interactions among some of the control variables, most obviously between the flow rates of O 2 and N 2O.

Choosing who shall not be treated in the NHS

In the face of severe resource constraints, health care systems are seeking both to control costs and to ensure maximum benefits for the resources consumed. The use of Quality Adjusted Life Years (QALYs) is becoming more widely advocated as a decision aid in the solution of resource allocation problems. The QALY combines two dimensions of health outcome—the quantity of life and its quality—in such a way that choices between different services with different purposes can be made using comparisons based on common units of measurement. The combination of these two dimensions allows comparisons between services with different objectives, such as curing and caring services. The QALY, however, lacks a third dimension which is vital to the decision-making process to which it is intended to contribute: the worth of a specific life relative to others. This paper presents results based on interviews of 719 residents of Cardiff drawn at random from the electoral register. The results suggest that further development of the novel methodology used to establish the relative value placed on various human lives is worthwhile. Evidence is given which indicates that the public consider lives to be of unequal worth. The results also show that these values are consistent for different types of choices phrased in different ways on a large number of control variables, implying the existence of a cultural stable value system which is a necessary prerequisite if consensus values of human life are to be used to assist decision-making in non-private health care systems. The paper suggests that it is right that the value system of those who pay for a group-funded health care system (such as the NHS) should guide choices between services. It is suggested that these choices are not the prerogative of professionals, whose view should carry no more weight than that of any other citizen. It is recognised that the suggestion that lives are not intrinsically of equal worth poses serious ethical problems for society, but the exploration of the value system of society, as advocated in this paper, may highlight issues which need further consideration.

Job Alienation and Well-Being

This paper analyzes the relationships between alienation conceived as monotonous, repetitive work and alienation as job-worker incongruence to a variety of measures of worker as well-being among a population of workers from Victoria, British Columbia. The data show weak relationships between work perceived as monotonous and general psychological and physical well-being and between alienation as job-worker incongruence and health. While weak in variance-explained terms, the relationships show the predicted patterns are robust and are independent of a large number of control variables. Percentage differences in well-being between the alienated and nonalienated workers are fairly substantial. Some societal implications of the findings are discussed.