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1 – 10 of over 6000Ingo Hoffmann and Christoph J. Börner
This paper aims to evaluate the accuracy of a quantile estimate. Especially when estimating high quantiles from a few data, the quantile estimator itself is a random number with…
Abstract
Purpose
This paper aims to evaluate the accuracy of a quantile estimate. Especially when estimating high quantiles from a few data, the quantile estimator itself is a random number with its own distribution. This distribution is first determined and then it is shown how the accuracy of the quantile estimation can be assessed in practice.
Design/methodology/approach
The paper considers the situation that the parent distribution of the data is unknown, the tail is modeled with the generalized pareto distribution and the quantile is finally estimated using the fitted tail model. Based on well-known theoretical preliminary studies, the finite sample distribution of the quantile estimator is determined and the accuracy of the estimator is quantified.
Findings
In general, the algebraic representation of the finite sample distribution of the quantile estimator was found. With the distribution, all statistical quantities can be determined. In particular, the expected value, the variance and the bias of the quantile estimator are calculated to evaluate the accuracy of the estimation process. Scaling laws could be derived and it turns out that with a fat tail and few data, the bias and the variance increase massively.
Research limitations/implications
Currently, the research is limited to the form of the tail, which is interesting for the financial sector. Future research might consider problems where the tail has a finite support or the tail is over-fat.
Practical implications
The ability to calculate error bands and the bias for the quantile estimator is equally important for financial institutions, as well as regulators and auditors.
Originality/value
Understanding the quantile estimator as a random variable and analyzing and evaluating it based on its distribution gives researchers, regulators, auditors and practitioners new opportunities to assess risk.
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Nada R. Sanders and Larry P. Ritzman
Accurate forecasting has become a challenge for companies operating in today's business environment, characterized by high uncertainty and short response times. Rapid…
Abstract
Accurate forecasting has become a challenge for companies operating in today's business environment, characterized by high uncertainty and short response times. Rapid technological innovations and e‐commerce have created an environment where historical data are often of limited value in predicting the future. In business organizations, the marketing function typically generates sales forecasts based on judgmental methods that rely heavily on subjective assessments and “soft” information, while operations rely more on quantitative data. Forecast generation rarely involves the pooling of information from these two functions. Increasingly, successful forecasting warrants the use of composite methodologies that incorporate a range of information from traditional quantitative computations usually used by operations, to marketing's judgmental assessments of markets. The purpose of this paper is to develop a framework for the integration of marketing's judgmental forecasts with traditional quantitative forecasting methods. Four integration methodologies are presented and evaluated relative to their appropriateness in combining forecasts within an organizational context. Our assessment considers human factors such as ownership, and the location of final forecast generation within the organization. Although each methodology has its strengths and weaknesses, not every methodology is appropriate for every organizational context.
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Francieli Tonet Maciel and Ana Maria Hermeto C. Oliveira
The purpose of this paper is to examine the effects of changes in the relative composition and in the segmentation between formal and informal labour on earnings differentials…
Abstract
Purpose
The purpose of this paper is to examine the effects of changes in the relative composition and in the segmentation between formal and informal labour on earnings differentials among women over the last decade in Brazil.
Design/methodology/approach
The authors follow Machado and Mata’s method to decompose the changes along the earnings distribution, with correction for sample selection and using microdata from the Demographic Census of 2000 and 2010. Informal labour was divided into informal salaried labour and self-employment, and both groups were compared with the formal labour separately.
Findings
The results indicate that, in both cases, an increase in earnings differentials in the bottom of the earnings distribution due to segmentation, suggesting that the returns to formal labour have grown relatively to informal labour during the period. On the other hand, earnings differentials decrease as one moves up the earnings distribution due to the composition effect, which is stronger on the top of the distribution relatively to the bottom. Furthermore, there are compensating differentials for self-employed women above the 30th quantile, which contributed to reduce the inequality between this group and formal workers.
Originality/value
The paper contributes to a better understanding of the changes taking place in female labour, shedding some light on how they affect different points along the earnings distribution. Furthermore, the adopted approach proposes a new application for the correction of sample bias in the context of quantile regression by employing a logit multinomial, and using the Demographic Census data.
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Current publication practices in the scholarly (International) Business and Management community are overwhelmingly anti-Popperian, which fundamentally frustrates the production…
Abstract
Purpose
Current publication practices in the scholarly (International) Business and Management community are overwhelmingly anti-Popperian, which fundamentally frustrates the production of scientific progress. This is the result of at least five related biases: the verification, novelty, normal science, evidence, and market biases. As a result, no one is really interested in replicating anything. In this essay, the author extensively argues what he believes is wrong, why that is so, and what we might do about this. The paper aims to discuss these issues.
Design/methodology/approach
This is an essay, combining a literature review with polemic argumentation.
Findings
Only a tiny fraction of published studies involve a replication effort. Moreover, journal authors, editors, reviewers and readers are not interested in seeing nulls and negatives in print. This replication crisis implies that Popper’s critical falsification principle is actually thrown into the scientific community’s dustbin. Behind the façade of all these so-called new discoveries, false positives abound, as do questionable research practices meant to produce all this allegedly cutting-edge and groundbreaking significant findings. If this dismal state of affairs does not change for the good, (International) Business and Management research is ending up in a deadlock.
Research limitations/implications
A radical cultural change in the scientific community, including (International) Business and Management, is badly needed. It should be in the community’s DNA to engage in the quest for the “truth” – nothing more, nothing less. Such a change must involve all stakeholders: scholars, editors, reviewers, and students, but also funding agencies, research institutes, university presidents, faculty deans, department chairs, journalists, policymakers, and publishers. In the words of Ioannidis (2012, p. 647): “Safeguarding scientific principles is not something to be done once and for all. It is a challenge that needs to be met successfully on a daily basis both by single scientists and the whole scientific establishment.”
Practical implications
Publication practices have to change radically. For instance, editorial policies should dispose of their current overly dominant pro-novelty and pro-positives biases, and explicitly encourage the publication of replication studies, including failed and unsuccessful ones that report null and negative findings.
Originality/value
This is an explicit plea to change the way the scientific research community operates, offering a series of concrete recommendations what to do before it is too late.
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Mateus Canniatti Ponchio, Nelson Lerner Barth and Felipe Zambaldi
Kamil Krasuski, Janusz Cwiklak and Marek Grzegorzewski
This paper aims to present the problem of the integration of the global positioning system (GPS)/global navigation satellite system (GLONASS) data for the processing of aircraft…
Abstract
Purpose
This paper aims to present the problem of the integration of the global positioning system (GPS)/global navigation satellite system (GLONASS) data for the processing of aircraft position determination.
Design/methodology/approach
The aircraft coordinates were obtained based on GPS and GLONASS code observations for the single point positioning (SPP) method. The numerical computations were executed in the aircraft positioning software (APS) package. The mathematical scheme of equation observation of the SPP method was solved using least square estimation in stochastic processing. In the research experiment, the raw global navigation satellite system data from the Topcon HiperPro onboard receiver were applied.
Findings
In the paper, the mean errors of an aircraft position from APS were under 3 m. In addition, the accuracy of aircraft positioning was better than 6 m. The integrity term for horizontal protection level and vertical protection level parameters in the flight test was below 16 m.
Research limitations/implications
The paper presents only the application of GPS/GLONASS observations in aviation, without satellite data from other navigation systems.
Practical implications
The presented research method can be used in an aircraft based augmentation system in Polish aviation.
Social implications
The paper is addressed to persons who work in aviation and air transport.
Originality/value
The paper presents the SPP method as a satellite technique for the recovery of an aircraft position in an aviation test.
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Dereje Mekonnen Bekele, Melkamu Teshome Ayana, Abdella Kemal Mohammed, Tarun Kumar Lohani and Mohammad Shabaz
To assess the impacts of climate change on stream flow and evaluation of reservoir performances, reliability, resilience and vulnerability (RRV) indices are contemplated…
Abstract
Purpose
To assess the impacts of climate change on stream flow and evaluation of reservoir performances, reliability, resilience and vulnerability (RRV) indices are contemplated. Precipitation, temperature (Tmax, Tmin), relative humidity and solar radiation are the hydrological and meteorological data which have been used extensively. Climate data like RCP2.6, RCP4.5 and RCP8.5 were evaluated for the base period 1976–2005 and future climate scenario for 2021–2050 and 2051–2080 as per the convenience.
Design/methodology/approach
The hydrologic engineering center hydrologic modeling system (HEC-HMS) model was used to simulate the current and future inflow volume into the reservoir. The model performance resulted as 0.76 Nash-Sutcliffe efficiency (NSE), 0.78 R2 and −3.17 D and during calibration the results obtained were 0.8 NSE, 0.82 R2 and 2.1 D. The projected climate scenario illustrates an increasing trend for both maximum and minimum temperature though a decreasing trend was documented for precipitation. The average time base reliability of the reservoirs was less than 50% without reservoir condition and greater than 50% for other conditions but volumetric reliability and resilience varies between 50% and 100% for all conditions. The vulnerability result of reservoirs may face shortage of flow ranging from 5.7% to 33.8%.
Findings
Evaluating reservoir simulation and hydropower generation for different climate scenarios by HEC-ResSim model, the energy generated for upper dam ranges from 349.4 MWhr to 331.2 MWhr and 4045.82 MWhr and 3946.74 MWhr for short and long-term future scenario, respectively. RCP for Tmax and Tmin goes on increasing whereas precipitation and inflow to reservoir decreases owing to increase in evapotranspiration. Under diverse climatic conditions power production goes on varying simultaneously.
Originality/value
This paper is original and all the references are properly cited.
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The purpose of this paper is based on implementation of Global Navigation Satellite System (GNSS) technique in civil aviation for recovery of aircraft position using Single Point…
Abstract
Purpose
The purpose of this paper is based on implementation of Global Navigation Satellite System (GNSS) technique in civil aviation for recovery of aircraft position using Single Point Positioning (SPP) method in kinematic mode.
Design/methodology/approach
The aircraft coordinates in ellipsoidal frame were obtained based on Global Positioning System (GPS) code observations for SPP method. The numerical computations were executed in post-processing mode in the Aircraft Positioning Software (APS) package. The mathematical scheme of equation observation of SPP method was solved using least square estimation in stochastic processing. In the experiment, airborne test using Cessna 172 aircraft on September 07, 2011 in the civil aerodrome in Mielec was realized. The aircraft position was recovery using observations data from Topcon HiperPro dual-frequency receiver with interval of 1 second.
Findings
In this paper, the average value of standard deviation of aircraft position is about 0.8 m for Latitude, 0.7 m for Longitude and 1.5 m for ellipsoidal height, respectively. In case of the Mean Radial Spherical Error (MRSE) parameter, the average value equals to 1.8 m. The standard deviation of receiver clock bias was presented in this paper and the average value amounts to 34.4 ns. In this paper, the safety protection levels of Horizontal Protection Level (HPL) and Vertical Protection Level (VPL) were also showed and described.
Research limitations/implications
In this paper, the analysis of aircraft positioning is focused on application the least square estimation in SPP method. The Kalman filtering operation can be also applied in SPP method for designation the position of the aircraft.
Practical implications
The SPP method can be applied in civil aviation for designation the position of the aircraft in Non-Precision Approach (NPA) GNSS procedure at the landing phase. The typical accuracy of aircraft position is better than 220 m for lateral navigation in NPA GNSS procedure. The limit of accuracy of aircraft position in vertical plane in NPA GNSS procedure is not available.
Social implications
This paper is destined for people who works in the area of aviation and air transport.
Originality/value
The work presents that SPP method as a universal technique for recovery of aircraft position in civil aviation, and this method can be also used in positioning of aircraft based on Global Navigation Satellite System (GLONASS) code observations.
Price indices for commercial real estate markets are difficult to construct because assets are heterogeneous, they are spatially dispersed and they are infrequently traded…
Abstract
Purpose
Price indices for commercial real estate markets are difficult to construct because assets are heterogeneous, they are spatially dispersed and they are infrequently traded. Appraisal-based indices are one response to these problems, but may understate volatility or fail to capture turning points in a timely manner. This paper estimates “transaction linked indices” for major European markets to see whether these offer a different perspective on market performance. The paper aims to discuss these issues.
Design/methodology/approach
The assessed value method is used to construct the indices. This has been recently applied to commercial real estate datasets in the USA and UK. The underlying data comprise appraisals and sale prices for assets monitored by Investment Property Databank (IPD). The indices are compared to appraisal-based series for the countries concerned for Q4 2001 to Q4 2012.
Findings
Transaction linked indices show stronger growth and sharper declines over the course of the cycle, but they do not notably lead their appraisal-based counterparts. They are typically two to four times more volatile.
Research limitations/implications
Only country-level indicators can be constructed in many cases owing to low trading volumes in the period studied, and this same issue prevented sample selection bias from being analysed in depth.
Originality/value
Discussion of the utility of transaction-based price indicators is extended to European commercial real estate markets. The indicators offer alternative estimates of real estate market volatility that may be useful in asset allocation and risk modelling, including in a regulatory context.
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Kelly Weeks, Matthew Weeks and Lauren Frost
The purpose of this paper is to examine the influence of race and social class on wage differentials between Black and White employees.
Abstract
Purpose
The purpose of this paper is to examine the influence of race and social class on wage differentials between Black and White employees.
Design/methodology/approach
A survey with four possible conditions (white/black target who was lower/middle class) was used in the study to examine the interaction between race and social class on compensation decisions.
Findings
The paper finds that there was a significant interaction between race and social class when predicting the percentage of pay increase given to employees. Specifically, there was a significant negative correlation between perceptions of social class and percentage of increase when the target was Black, but there was no such correlation when the target was White.
Research limitations/implications
The sample was 95.6 percent White and did not consist of managerial employees in actual compensation decisions; however, it shows evidence that people are affected by their perceptions of social class and race when making such decisions.
Practical implications
Policy makers should not forget that perceived social class might interact with race to influence discriminatory decisions in workplaces. This research suggests that Black employees who are perceived to be middle class are discriminated against more than those who are perceived to be lower class. Businesses need to be aware of unintentional biases that may be plaguing their managers and train them to avoid such biases.
Originality/value
This paper contributes new insight into the literature on the wage gap between Black and White employees by showing the interaction between race and perceived social class when predicting pay increases.
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