Consistency of Hedonic Price Indexes with Unobserved Characteristics

Hedonic regressions are prone to omitted variable bias. The estimation of price relatives for new and disappearing goods using hedonic imputation methods involves taking ratios of hedonic models. This may lead to a situation where the omitted variable bias in each of the hedonic regressions offset each other. This study finds that the single imputation hedonic method estimates inconsistent price relatives, while the double imputation method may produce consistent price relatives depending on the behavior of unobserved characteristics in the comparison periods. The study outlines a methodology to test whether double imputation price relatives are consistent. The results of this study have implications with regard to the construction of quality adjusted indexes.Hedonic imputation method; omitted variable bias; model selection; quality adjusted price indexes; new and disappearing goods

Life Cycle Pricing and the Measurement of Inflation

This paper explores the extent to which goods follow systematic pricing patterns over their life cycle. The theoretical literature, and anecdotal evidence, often suggests that new products are often introduced at high prices which decline as the good ages while, older goods exit the market at a discount. We outline and apply a smoothing-spline approach to the estimation of life cycle price effects using data on two different types of goods (desktop and laptop computers, and personal digital assistants). We interpret these results within a simple conceptual framework and find evidence for the existence of significant life cycle pricing effects. This implies that hedonic pricing functions that exclude age are misspecified. Furthermore, in order to eliminate biases in price indexes, samples must be constructed carefully. Using a simulation we show that the bias introduced by the traditional match-model method may be non-trivial.Product life cycle; Hedonic regression; Price index; Spline smoothing; Scanner data

Prices over the Product Life Cycle: An Empirical Analysis

This paper explores the extent to which goods follow systematic pricing patterns over their life cycle. The theoretical literature, and anecdotal evidence, suggests that new products are often introduced at high prices which decline as the good ages while, older goods exit the market at a discount. We outline and apply a smoothing-spline approach to the estimation of life cycle pricing effects using data on two different types of goods; supermarket products (beer, canned soup and cereals) and high-tech goods (desktop and laptop computers, and personal digital assistants). We interpret these results within a simple conceptual framework and find evidence for the existence of significant life cycle pricing effects. This implies that hedonic pricing functions which exclude age are misspecified. Furthermore, in order to eliminate bias price index samples must be constructed carefully. Using a simulation we show that the bias introduced by the traditional match-model method may be non-trivial.Product life cycle; Hedonic regression; Price index; Spline smoothing

Improving International Comparisons of Real Output: The ICP 2005 Benchmark and its Implications for China

The latest round of the International Comparisons Program (ICP 2005) compares the purchasing power of currencies and real output of 146 countries. Using price quote data from nine countries in the Asia-Pacific region, we consider ways of improving the methods used in ICP 2005 and new applications of these methods (e.g., for calculating rural-urban price differentials). The most striking result in ICP 2005 was that China came out 40 percent smaller than previously thought. We also evaluate the extent to which this finding can be attributed to excessive sampling of prices in China from urban areas or of unrepresentative products.International Comparisons Program; Country-Product-Dummy Method; Price Index; Basic Heading; Urban-Rural Price Differences; Representative and Unrepresentative Products; Asia-Pacific Region

Advanced Filler Network Characterization in Rubber

The present work is aimed at introducing new characterization techniques in filled rubber compounds. Rubber fillers such as carbon black are often used to enhance the physical properties of rubber compounds. With a sufficient amount of carbon black, a percolated filler network is formed, spanning the volume of the rubber compound. This phenomenon not only significantly improves the mechanical material behaviour, but also introduces a more complex mechanical response. Further enhancement is possible with the addition of reinforcing resins such as Novolaks, phenol–formaldehyde resins with a formaldehyde-to-phenol molar ratio of less than one. Based on the systematic studies performed, the two reinforcing materials are observed to exhibit synergistic behaviour resulting from their physical and chemical interaction. The reinforcing resin modifies the activity of the filler surface creating a more compact filler network. This leads to a lower filler network percolation threshold as well as increasing the reinforcing behaviour. This conclusion was derived from various thermo-mechanical measurements such as temperature stress scanning relaxation (TSSR) and dynamic mechanical analysis (DMA). The findings were also validated with advanced microscopical techniques such as atomic force microscopy (AFM) and transmission electron microscopy (TEM). A direct consequence of the filler network is a strain dependent behaviour such as the dynamic and quasi-static strain dependent softening effects known as Payne and Mullins effects, respectively. Within the conventional dynamic mechanical analysis (DMA) of rubber compounds, the mechanical response signal is often assumed to be rheologically linear (sinusoidal function) since in Fourier space, the first harmonic is more pronounced than the subsequent higher harmonics. However, valuable information contained in the higher harmonics can be utilised in order to further characterise the compound properties. One such approach is the large amplitude oscillatory shear (LAOS) technique which analyses the harmonics as a function of large strain deformation. While several studies have contributed to the understanding of this strain dependent nonlinearity, less emphasis was placed on the nonlinearity of the frequency domain. Utilising a resonance-based high frequency DMA, nonlinearities in the frequency domain were established by the observation of the superharmonic resonance, for the first time in rubber technology. Two distinct nonlinearities were observed, polymer induced nonlinearity and filler induced nonlinearity. The new method based on the superharmonic resonance has been successfully applied to characterise the filler network through the evaluation of the microdispersion of carbon black and its interaction with reinforcing resins.Die vorliegende Arbeit hat das Ziel, innovative Methoden zur Charakterisierung von gefüllten Kautschukmischungen einzuführen. Füllstoffe, wie Ruß, werden in Kautschuk eingesetzt, um seine physikalischen Eigenschaften zu verstärken. Mit einer ausreichenden Menge an Ruß wird ein perkolierendes Netzwerk erzeugt, das das Volumen der Kautschukmischung durchdringt. Diese Erscheinung verstärkt nicht nur das mechanische Materialverhalten, sondern führt zu einer komplexeren mechanischen Reaktion. Eine weitere Verstärkung ist durch den Einsatz netzwerkbildender Harze möglich, z.B. von Novolaken, Phenolharzen mit einem Formaldehyd-Phenol-Verhältnis kleiner eins. Auf der Basis von systematischen Studien wird ein synergistisches Verhalten der beiden verstärkenden Materialien infolge ihrer physikalischen und chemischen Wechselwirkung beobachtet. Das Verstärkungsharz verändert die Aktivität der Füllstoffoberfläche und erzeugt damit ein kompakteres Füllstoffnetzwerk. Dies führt zu einer reduzierten Perkolationsschwelle sowie zu einer zusätzlich höheren Verstärkung. Diese Schlussfolgerung wurde aus Messungen mit verschiedenen thermomechanischen Verfahren abgeleitet, wie der anisothermen Spannungsrelaxation (TSSR) und der dynamisch-mechanischen Analyse (DMA). Die Ergebnisse wurden auch mit anspruchsvollen mikroskopischen Techniken validiert, wie der Rasterkraftmikroskopie (AFM) und Transmissionselektronenmikroskopie (TEM). Eine direkte Folge des Füllstoffnetzwerks ist die Entstehung eines dehnungsabhängigen Verhaltens, das als dynamischer oder quasi-statischer Erweichungseffekt beobachtet und jeweils als Payne- oder Mullins-Effekt bezeichnet wird. Bei der dynamisch-mechanischen Analyse (DMA) von Kautschukmischungen wird häufig eine Linearität der Antwort in Bezug auf das angelegte Verformungssignal angenommen, da die Stärke der ersten Harmonischen viel höher ist als die der nachfolgenden Harmonischen. Es gibt jedoch wertvolle Informationen in den höheren Harmonischen, die verwendet werden könnten, um die Materialeigenschaften weiter zu charakterisieren. Ein solcher Ansatz ist die LAOS-Technik (engl. Large Amplitude Oscillatory Shear), mit der die Harmonischen als Funktion der Dehnung analysiert werden. Während einige Studien bereits zum Verständnis dieses dehnungsabhängigen Phänomens beigetragen haben, wurde weniger Wert auf die Nichtlinearität im Frequenzbereich gelegt. Unter Verwendung einer resonanzbasierten Hochfrequenz-DMA wurden erstmals in der Kautschuktechnologie Nichtlinearitäten im Frequenzraum durch Beobachtung von superharmonischen Resonanzen festgestellt. Zwei unterschiedliche Typen von Nichtlinearitäten wurden beobachtet, die polymerinduzierte und die füllstoffinduzierte Nichtlinearität. Die neue Methode auf der Basis der superharmonischen Resonanz wurde zur Charakterisierung des Füllstoffnetzwerkes durch Bewertung der Mikrodispersion von Ruß und dessen Wechselwirkung mit verstärkenden Harzen erfolgreich eingesetzt

Flexible Spatial and Temporal Hedonic Price Indexes for Housing in the Presence of Missing Data

We propose a flexible hedonic methodology for computing house price indexes that uses multiple imputation (MI) to account for missing data (a huge problem in housing data sets). Ours is the first study to use MI in this context. We also allow for spatial correlation, include interaction terms between characteristics, between regions and periods, and between regions and characteristics, and break the regressions up into overlapping blocks of five consecutive periods (quarters in our case). These features ensure that the shadow prices are flexible both across regions and time. This flexible structure makes the derivation of price indexes from the estimated regression equations far from straightforward. We develop innovative methods for resolving this problem and for splicing the overlapping blocks together to generate the overall panel results. We then use our methodology to construct temporal and spatial price indexes for 15 regions in Sydney, Australia on a quarterly basis from 2001 to 2006 and combine them to obtain an overall price index for Sydney. Our hedonic indexes differ quite significantly from the official index for Sydney published by the Australian Bureau of Statistics. We also find clear evidence of convergence in prices across regions from 2001-3 (while prices were rising), and divergence thereafter. We conclude by exploring some of the implications of these empirical findings.Real estate; House prices; Hedonic price index; Missing data; Multiple imputation; Spatial correlation

Physics of Bio-electrical Impedance Analysis: Phase Angle and its Application

Bioelectrical impedance   analysis is an easy technique to evaluate the changes in the body composition. In BIA a small amount of electric current is passed through the body and from electrical properties of human body, Biological values or quantities are calculated, Human body behaves like electric circuit, it acts like RC series and parallel circuit. Here in this review paper these circuits are discussed and then try to implement them on human body to find the composition of human body. The science of this technique is presented that may be helpful   for further research in this field... From BIA Phase angle is calculated. Phase angle is very important in clinical research and it can be used as an indicator of health. Role of Phase angle in different disease like cancer and HIV, and its application to monitor and evaluate the patient condition and its role as a prognostic indicator is discussed in this review article using the studies of different researchers. Phase angle can be used as survival indicator in advance cancer patient and HIV. Phase angle can be used to monitor the malnutrition in patient of HIV.Keywords: Phase angle, Prognostic indicator, Cancer and HIV, body compositio

Hardware realization and PID control of multi-degree of freedom articulated robotic arm

A robotic manipulator is the most important component in an industrial environment for autonomous execution of tasks. Given the repoted fact that a PID (Proportional-Integral-Derivative) will continue to be the main workhorse in the automation sector, the present paper deals with designing and realizing this control law. A custom-developed pseudo-industrial platform AUTAREP (AUTonomous Articulated Robotic Educational Platform) centered on a 6DOF (Six Degree of Freedom) manipulator is considered. The derived kinematic and dynamic models of the arm form the basis of MATLAB-based control simulation. The control law after discretization is also implemented on embedded hardware. When subject to various inputs, result of trajectory tracking in the form of output responses, demonstrate superior performance in transient as well as steady state. The stability and convergent behavior of the outputs is also observed, thus highlighting efficacy of proposed approach

Causes, Effects, and Remedies in Conflict Management

While workplace conflicts have been widely studied in the literature, this researchprovides a holistic view of the causes and effects of such, and how managers or amanagement can resolve the conflicts among their teams and organization througha detailed, multidimensional framework carried out on one of the biggest textilefirms of Pakistan. With an initial sample of 145 respondents, 37 questionnaireswere dropped because of invalid and incomplete answers; therefore, the studywas carried out on 108 respondents. Conflicts are a part of human nature, butmanagement should play an important role in dealing with these issues, as therecan be enormous chances of conflicts due to a diverse workforce. Conflict alsoresults in poor work performance and low productivity; therefore, it’s suggestedto create teams or groups which may encourage a competitive culture in theorganization. Additionally, a few remedies are identified, which may resolve someissues; managers must look at those techniques for a better culture.&nbsp