Search results

Research in the area of forecasting and stock inventory control for intermittent demand is designed to provide robust models for the underlying demand which appears at random, with some time periods having no demand at all. Croston’s method is a popular technique for these models and it uses two single exponential smoothing (SES) models which involve smoothing constants. A key issue is the choice of the values due to the sensitivity of the forecasts to changes in demand. Suggested selections of the smoothing constants include values between 0.1 and 0.3. Since an ARIMA model has been illustrated to be equivalent to SES, an optimal smoothing constant can be selected from the ARIMA model for SES. This chapter will conduct simulations to investigate whether using an optimal smoothing constant versus the suggested smoothing constant is important. Since SES is designed to be an adapted method, data are simulated which vary between slow and fast demand.

This chapter introduces dividend smoothing, presents theories to explain dividend smoothing behavior, and analyzes how different levels of business environment affect dividend smoothing. First, dividend smoothing describes a mechanism in which a firm is reluctant to reduce dividends and only increases dividends when its earnings increase permanently. In practice, dividend smoothing behavior is found in both developed and developing countries. Firms in developed countries are more likely to smooth dividends than those in developing countries. Second, although Miller and Modigliani (1961) posit that investors are indifferent between stable and unstable dividend payments in a perfect environment, market frictions in the real world make stable and unstable dividends have different effects on firm value. Three common frictions are information asymmetry, agency problem, and investors' demand for income smoothing. Due to information asymmetry between insiders and outsiders, firms tend to smooth their dividends to signal outside investors about their quality. In addition, dividend smoothing may be the substitute for weak corporate governance and/or the outcome of free cash absorption behavior. Besides, dividends are more convenient for investors' consumption; therefore, firms are more likely to smooth dividends in order to satisfy investors' demand for smooth income. Finally, as a special dividend decision, dividend smoothing is also affected by an internal micro (industry) and macro-environment. Dividend smoothing theories are the behind mechanisms to explain these effects.

Demand forecasting has long been an imperative tenet in production planning especially in a make-to-order environment where a typical manufacturer has to balance the issues of holding excessive safety stocks and experiencing possible stockout. Many studies provide pragmatic paradigms to generate demand forecasts (mainly based on smoothing forecasting models.) At the same time, artificial neural networks (ANNs) have been emerging as alternatives. In this chapter, we propose a two-stage forecasting approach, which combines the strengths of a neural network with a more conventional exponential smoothing model. In the first stage of this approach, a smoothing model estimates the series of demand forecasts. In the second stage, general regression neural network (GRNN) is applied to learn and then correct the errors of estimates. Our empirical study evaluates the use of different static and dynamic smoothing models and calibrates their synergies with GRNN. Various statistical tests are performed to compare the performances of the two-stage models (with error correction by neural network) and those of the original single-stage models (without error-correction by neural network). Comparisons with the single-stage GRNN are also included. Statistical results show that neural network correction leads to improvements to the forecasts made by all examined smoothing models and can outperform the single-stage GRNN in most cases. Relative performances at different levels of demand lumpiness are also examined.

We investigate whether smooth robust methods for forecasting can help mitigate pronounced and persistent failure across multiple forecast horizons. We demonstrate that naive predictors are interpretable as local estimators of the long-run relationship with the advantage of adapting quickly after a break, but at a cost of additional forecast error variance. Smoothing over naive estimates helps retain these advantages while reducing the costs, especially for longer forecast horizons. We derive the performance of these predictors after a location shift, and confirm the results using simulations. We apply smooth methods to forecasts of UK productivity and US 10-year Treasury yields and show that they can dramatically reduce persistent forecast failure exhibited by forecasts from macroeconomic models and professional forecasters.

New asymptotic approximations are established for the Wald and t statistics in the presence of unknown but strong autocorrelation. The asymptotic theory extends the usual fixed-smoothing asymptotics under weak dependence to allow for near-unit-root and weak-unit-root processes. As the locality parameter that characterizes the neighborhood of the autoregressive root increases from zero to infinity, the new fixed-smoothing asymptotic distribution changes smoothly from the unit-root fixed-smoothing asymptotics to the usual fixed-smoothing asymptotics under weak dependence. Simulations show that the new approximation is more accurate than the usual fixed-smoothing approximation.

Purpose: In this chapter, the author evaluates the association between bank loan loss provisions (LLP) and the pre-provisions earnings of UK banks during the first-wave of the COVID-19 pandemic. A positive co-movement between the two variables indicates income smoothing.

Methodology: Graphical analysis, correlation analysis and regression analysis are used to assess the relationship between income smoothing and bank provisions among UK systemic banks.

Findings: The findings show that LLP have an inverted V-shaped property during the first-wave of COVID-19 pandemic. LLP reached its highest level at the peak of the pandemic in Q2 2020 and declined in the subsequent quarters. The regression results show that LLP are positively related to pre-provisions earnings during the pandemic quarters and in the pre-pandemic quarters. The relationship is stronger in the pandemic quarters and indicates higher income smoothing in the pandemic quarters. The correlation results also show a strong positive correlation between bank provisions and pre-provisions earnings in the pandemic period. In the individual bank analysis, three of the four systemic banks exhibit higher income smoothing during the pandemic quarters.

Implication: UK systemic banks engaged in earnings management as a coping mechanism to mitigate the effect of the pandemic on their profits.

Need for the study/originality: This chapter is the first to provide a preliminary analysis of income smoothing among banks during the early stages of the COVID-19 pandemic.

Product success is contingent on forecasting when a product is needed and how it should be offered. Forecasting accuracy is contingent on the correct forecasting technique. Using supermarket data across two product categories, this chapter shows that using a bevy of forecasting methods improves forecasting accuracy. Accuracy is measured by the mean absolute percentage error. The optimal methods for one consumer goods product may be different than for another. The best model varied from sophisticated, most such as autoregressive integrated moving average (ARIMA) and Holt–Winters to a random walk model. Forecasters must be proficient in multiple statistical techniques since the best technique varies within a categories, variety, and product size.

There is a growing literature in nonparametric econometrics in the recent two decades. Given the space limitation, it is impossible to survey all the important recent developments in nonparametric econometrics. Therefore, we choose to limit our focus on the following areas. In Section 2, we review the recent developments of nonparametric estimation and testing of regression functions with mixed discrete and continuous covariates. We discuss nonparametric estimation and testing of econometric models for nonstationary data in Section 3. Section 4 is devoted to surveying the literature of nonparametric instrumental variable (IV) models. We review nonparametric estimation of quantile regression models in Section 5. In Sections 2–5, we also point out some open research problems, which might be useful for graduate students to review the important research papers in this field and to search for their own research interests, particularly dissertation topics for doctoral students. Finally, in Section 6 we highlight some important research areas that are not covered in this paper due to space limitation. We plan to write a separate survey paper to discuss some of the omitted topics.

When forecasting intermittent demand the method derived by Croston (1972) is often cited. Previous research favorably compared Croston's forecasting method for demand with simple exponential smoothing assuming a nonzero demand occurs as a Bernoulli process with a constant probability. In practice, however, the assumption of a constant probability for the occurrence of nonzero demand is often violated. This research investigates Croston's method under violation of the assumption of a constant probability of nonzero demand. In a simulation study, forecasts derived using single exponential smoothing (SES) are compared to forecasts using a modification of Croston's method utilizing double exponential smoothing to forecast the time between nonzero demands assuming a normal distribution for demand size with different standard deviation levels. This methodology may be applicable to forecasting intermittent demand at the beginning or end of a product's life cycle.

This survey focuses on two families of nonlinear vector time series models, the family of vector threshold regression (VTR) models and that of vector smooth transition regression (VSTR) models. These two model classes contain incomplete models in the sense that strongly exogeneous variables are allowed in the equations. The emphasis is on stationary models, but the considerations also include nonstationary VTR and VSTR models with cointegrated variables. Model specification, estimation and evaluation is considered, and the use of the models illustrated by macroeconomic examples from the literature.