an integrated mixture of local experts model for demand forecasting abstract demand forecasting is an important issue in the supply chain planning process due to its usage for efficiently managing different planning tasks the common techniques adopted to perform such task are easy to use forecasting methods performed in computerised systems with minimum human intervention such as the simple exponential smoothing concerning the drawbacks of these modelling approaches past evidence suggests that they have been less successful in predicting short term fluctuations on demand in this work the simple exponential smoothing method is employed to build an integrated mixture of local experts model imlem for demand forecasting using as independent variable a lagged gross domestic product gdp indicator the imlem is usually employed to deal with rapidly changing situations and it is used in this work to improve the performance of the forecasts by providing a way to take into account short term fluctuations on demand due to changes on economic activity growth within an easy to use forecasting method the proposed method was applied on one step ahead demand forecasting for a brazilian beverage manufacturer for 130 non seasonal stock keeping units skus and the accuracy of the generated forecasts allowed to reduce the forecasting errors the obtained results also supported the decision making process by aiding demand planners concerning how to react to short term fluctuations on demand

surplus distribution from the introduction of a biotechnology innovation we examine the distribution of welfare from the introduction of bt cotton in the united states in 1996 the welfare framework explicitly recognizes that research protected by intellectual property rights generates monopoly profits and makes it possible to partition these rents among consumers farmers and the innovating input firms we calculate a total increase in world surplus of 240 3 million for 1996 of this total the largest share 59 went to u s farmers the gene developer monsanto received the next largest share 21 followed by u s consumers 9 the rest of the world 6 and the germplasm supplier delta and pine land company 5

structural changes and the us money demand function previous literature on the stability of the us money demand function suggests mixed results in this article we study the stability of the money demand function from the standpoint of structural changes in the function we first investigate if a stable money demand function can be found for the us for the period from the first quarter of 1959 to the fourth quarter of 2000 the results show that a stable long run money demand function does not exist for the sample period under consideration we then estimate unknown structural break points in the variables of the money demand function using bai and perron s 1998 method and test if there is a stable relationship in each sub sample period of the break points the results show that a stable relationship exists for each sub sample period the estimated income elasticity and interest rate semi elasticity are relatively smaller than ball s 2001 estimates but consistent with his argument

three decades of money demand studies differences and similarities by analysing almost 1000 money demand estimations this paper attempts to summarize the diverse findings of the literature on this topic using both descriptive statistics and meta regressions several stylized facts are derived about the two most prominent determinants of money demand income and interest rate elasticities in particular it is shown we show that the size and signs of average elasticities are systematically related to the choice of included variables e g m1 or m3 short run or long run interest rates the country grouping e g usa versus germany and the empirical specification e g the inclusion of one or two interest rates

ldc agriculture nonparametric malmquist productivity indexes abstract this paper examines changes in agricultural productivity in 18 developing countries over the period 1961 1985 we use the nonparametric output based malmquist index to examine whether the results from such an approach confirm results from other methods that have indicated declining agricultural productivity in less developed countries ldcs the results confirm previous findings indicating that at least half of these countries have experienced productivity declines in agriculture we also found that those countries that tax agriculture most heavily had the most negative rates of productivity change

forecasting with multivariate temporal aggregation the case of promotional modelling demand forecasting is central to decision making and operations in organisations as the volume of forecasts increases for example due to an increased product customisation that leads to more skus being traded or a reduction in the length of the forecasting cycle there is a pressing need for reliable automated forecasting conventionally companies rely on a statistical baseline forecast that captures only past demand patterns which is subsequently adjusted by human experts to incorporate additional information such as promotions although there is evidence that such process adds value to forecasting it is questionable how much it can scale up due to the human element instead in the literature it has been proposed to enhance the baseline forecasts with external well structured information such as the promotional plan of the company and let experts focus on the less structured information thus reducing their workload and allowing them to focus where they can add most value this change in forecasting support systems requires reliable multivariate forecasting models that can be automated accurate and robust this paper proposes an extension of the recently proposed muliple aggregation prediction algorithm mapa which uses temporal aggregation to improve upon the established exponential smoothing family of methods mapa is attractive as it has been found to increase both the accuracy and robustness of exponential smoothing the extended multivariate mapa is evaluated against established benchmarks in modelling a number of heavily promoted products and is found to perform well in terms of forecast bias and accuracy furthermore we demonstrate that modelling time series using multiple temporal aggregation levels makes the final forecast robust to model misspecification

a systemic approach to modelling and estimating demand for money ies this article uses a consumer theory based systemic approach to model the demand for monetary liquid asset holdings in chile we implement the suggestions and caveats of aggregation theory for the estimation of a demand system for liquid assets monies in static dynamic and time varying parameters setups our results are robust and theoretically consistent with consumer theory restrictions as a system derived from a utility maximizing framework and a quasi concave utility function in our estimations we find stability of interest rate elasticities in contrast to previous related literature we also document evidence that long short maturity rates are associated to less more liquid assets

investigating the added value of integrating human judgement into statistical demand forecasting systems abstract whilst the research literature points towards the benefits of a statistical approach business practice continues in many cases to rely on judgmental approaches for demand forecasting in today s dynamic environment it is especially relevant to consider a combination of both approaches however the question remains as to how this combination should occur this study compares two different ways of combining statistical and judgmental forecasting employing real life data from an international publishing company that produces weekly forecasts on regular and exceptional products two forecasting methodologies that are able to include human judgment are compared in a restrictive judgement model expert predictions are incorporated as restrictions on the forecasting model in an integrative judgment model this information is taken into account as a predictive variable in the demand forecasting process the proposed models are compared on error metrics and analysed with regard to the properties of the adjustments direction size and of the forecast itself volatility periodicity the integrative approach has a positive effect on accuracy in all scenarios however in those cases where the restrictive approach proved to be beneficial the integrative approach limited these beneficial effects the study links with demand planning by using the forecasts as input for an optimization model to determine the ideal number of skus per point of sale pos making a distinction between sku forecasts and sku per pos forecasts importantly this enables performance to be expressed as a measure of profitability which proves to be higher for the integrative approach than for the restrictive approach

the meta production function approach to technological change in world agriculture abstract an alternative meta production function for agriculture is estimated with the cross section data for 43 countries and three years 1960 1970 and 1980 constructed and used by kawagoe hayami and ruttan and hayami and ruttan in their studies by allowing for country specific efficiency factors and using a flexible functional form the transcendental logarithmic production function strikingly different results from those of kawagoe hayami and ruttan are obtained in particular it is found that elasticity of output with respect to machinery is variable and the degree of local returns to scale is not constant and increases with the usage of machinery

modeling u s households demands for liquid wealth in an era of financial change money demand models overpredicted m2 growth in the united states from 1990 to 1993 the authors examine this overprediction using a model of households demands for liquid wealth the model is a dynamic generalization of the aids model of angus deaton and john muellbauer 1980 the authors find that the own price elasticity of money rose substantially after 1990 they also find important cross price elasticities of money with respect to other liquid financial assets notably with respect to mutual funds incorporating these and other features helps explain nearly 50 percent of the shortfall in m2 growth over the period in question

productivity growth in world agriculture sources and constraints during the last half century advances in crop production came from expansion in areas irrigated from more intensive application of fertilizers and crop protection chemicals and from crop varieties that were more responsive to technical inputs and management advances in animal production came from genetic improvements and advances in animal nutrition differences among developed and developing countries in output per hectare and per worker have widened if these gaps are to be narrowed agricultural research capacity in developing countries will have to be substantially strengthened

productivity growth in u s agriculture a postwar perspective there has been a long standing fascination with productivity trends in u s agriculture in part this stems from the historical importance of agriculture to the economy but it also reflects economists early and continued interest in quantifying the rate of return to society s sizable investment in agricultural r d the sum of government sponsored and private sector r d investment in agriculture is estimated to have been 268 million in 1953 in that year total r d investment in the economy from all sources amounted to 5 1 billion 2 excluding defense and space related r d which accounted for approximately half of the u s total in the early fifties 3 r d expenditures dedicated to agriculture equaled approximately 10 of total u s investment in r d from all sources

the intercountry agricultural production function and productivity differences among countries abstract the sources of differences in labor productivity in agriculture between developed countries dc s and less developed countries ldc s are identified by estimating an aggregate agricultural production function based on cross county data for 1960 1970 and 1980 the production function was found to be stable over the entire period agriculture in the dc s was characterized by increasing returns and in the ldc s by constant returns to scale the results imply that unfavorable man land ratios do not represent an immediate barrier to rapid agricultural development in the low income ldc s but they may create a serious agricultural adjustment problem as those countries advance into the middle income range

testing for homogeneity in demand systems when the regressors are nonstationary an implication of optimizing theory is that demand functions are homogeneous of degree zero in prices and nominal income evidence based on estimations of demand systems has repeatedly found this restriction to be rejected by the data however the hypothesis is often formulated in terms of regressors that are non stationary this paper re examines the evidence for homogeneity in light of recent developments in time series econometrics with special emphasis on the treatment of trends we find the demand system to be stochastically but not deterministically cointegrated using techniques developed for estimating cointegrating vectors in the presence of deterministic trends we re estimate the demand system and find that homogeneity holds in many cases

agricultural productivity in developing countries abstract this paper examines changes in agricultural productivity in 18 developing countries over the period 1961 1985 we use a nonparametric output based malmquist index and a parametric variable coefficients cobb douglas production function to examine whether our estimates confirm results from other studies that have indicated declining agricultural productivity in ldcs the results confirm previous findings indicating that at least half of these countries have experienced productivity declines in agriculture

a model for selecting the appropriate level of aggregation in forecasting processes abstract demand forecasting is a major issue in several industrial sectors a relevant choice for companies is the proper level of forecast aggregation forecasters need to properly identify what is the object of the forecasting process in terms of time bucket e g forecasts are produced on a daily level or on weekly one set of items the demand refers to e g single item or group of items set of locations the demand refers to e g single store or chain of stores managers can follow two basic approaches on the one hand they can adopt a detailed forecasting approach i e they can forecast demand for the item at the store by simply looking at the demand for the specific item store on the other hand they can adopt an aggregated forecasting approach in this paper we aim at figuring out what is the balance between the strengths and weaknesses of these two options and to identify the contingent variables that might lead managers to adopt one approach rather than the other in this paper we study the aggregation across locations by evaluating the components of forecasting error under the assumption of stationary demand finally we suggest metrics that one can adopt to support the choice of the appropriate forecasting process thus providing help to managers in defining the proper level of aggregation for a specific situation

the effects of integrating management judgement into out levels in or out of context physical inventories constitute a significant proportion of companies investments in today s competitive environment the trade off between customer service levels and inventory reserves is addressed in practice by statistical inventory software solutions given the tremendous number of stock keeping units skus that contemporary organizations deal with such solutions are fully automated however empirical evidence suggests that managers habitually judgementally adjust the output of such solutions such as replenishment orders or re order levels this research is concerned with the value being added or not when statistically derived inventory related decisions order up to out levels in particular are judgementally adjusted we aim at developing our current understanding on the effects of incorporating human judgement into inventory decisions to our knowledge such effects do not appear to have been studied empirically before and this is the first endeavour to do so a number of research questions are examined and a simulation experiment is performed using an extended database of approximately 1 800 skus from the electronics industry in order to evaluate human judgement effects the linkage between adjustments and their justification is also evaluated given the apparent lack of comprehensive empirical evidence in this area including the field of demand forecasting this is a contribution in its own right insights are offered to academics to facilitate further research in this area practitioners to enable more constructive intervention into statistical inventory solutions and software developers to consider the interface with human decision makers

the effects of integrating management judgement into intermittent demand forecasts empirical research suggests that quantitatively derived forecasts are very frequently judgementally adjusted nevertheless little work has been conducted to evaluate the performance of these judgemental adjustments in a practical demand sales context in addition the relevant analysis does not distinguish between slow and fast moving items currently there are neither conceptual developments nor empirical evidence on the issue of integrating judgements and statistical forecasts for slow intermittent demand items moreover no results have ever been reported on the stock control implications of these human judgements our work analyses monthly intermittent demand forecasts for the uk branch of a major international pharmaceutical company the company relies upon a commercially available statistical forecasting system to produce forecasts that are subsequently judgementally adjusted based on marketing intelligence gathered by the company forecasters the benefits of the intervention are evaluated by comparing the actual sales to system and final forecasts using both forecast accuracy and inventory control accuracy implication metrics our study allows insights to be gained on potential improvements to intermittent demand forecasting processes and subsequently the design effectiveness of forecasting support systems

productivity growth technical progress and efficiency change in industrialized countries this paper analyzes productivity growth in 17 oecd countries over the period 1979 1988 a nonparametric programming method activity analysis is used to compute malmquist productivity indexes these are decomposed into two component measures namely technical change and efficiency change we find that u s productivity growth is slightly higher than average all of which is due to technical change japan s productivity growth is the highest in the sample with almost half due to efficiency change jel c43 d24 in this paper we apply recently developed

consumer theory and the demand for money the following sections are included introductionthe definition of moneythe microeconomic theory of a monetary economythe aggregation theoretic approach to money demandindex number theorythe links between aggregation theory index number theory and monetary theoryunderstanding the new divisia aggregatesthe optimal level of monetary subaggregationeconometric considerationsapproximating the monetary services subutility functionan exampleempirical dimensionsempirical comparisons of index numbersempirical results for the demand system approachextensionsconclusions this abstract was borrowed from another version of this item

evaluating the linearized almost ideal demand system linearizing the almost ideal demand system laids by recourse to the stone share weighted price index is common practice two issues are addressed here first scrutiny of the errors in variables implications of the linearization reveals that not only is the sur estimator inconsistent but a consistent iv estimator cannot be constructed second some alternatives to the green alston elasticities specifically designed for the laids model are developed but neither these nor the green alston elasticities are found to have any advantages over the conventional elasticity formulae some errors in the green alston 1990 paper are corrected the inconsistency and elasticity issues are documented by a monte carlo investigation