Policy issues in the development of telecommunications

The paper examines the specific features of the telecommunications system which determine its character, and the regulatory issues which arise out of a situation of potential conflict between the telecommunications network operators (PITs) and the providers and consumers of value added services transacted on the network. It looks at the policy options available to reconcile such conflicts, and at how EC policies are shaping the future of the European telecommunications ststem. It concludes that current development in telematics are aimed mainly at business users, and that safeguards for the private custormer will be necessary in order to ensure the provision of a socially equitable service.     

The Effect of Demand on Stock Prices: Evidence from Index Fund Rebalancing

I examine the effect of demand on stock prices by analyzing the conversion of the TIPs 35 and TIPs 100 exchange‐traded funds into the i60 Fund. This conversion occurred at the Toronto Stock Exchange on March 6, 2000. Forty stocks of the TIPs 100 Fund that were not members of the new units of the i60 Fund were sold to complete this conversion. I find that a decrease in demand produced a permanent stock price decline, which was accompanied by significant abnormal trading volume. The results provide support for the downward‐sloping demand curve hypothesis.     

Analysis of the intertemporal behaviour of parameter estimates from a model of the United States economy

Zusammenfassung Untersuchungen der Veranderungen von Parametersch?tzungen im Zeitablauf an einem Modell der Volkswirtschaft der Vereinigten Staaten. — Prognosen aufgrund ?konometrischer Modelle erfordern eine standige Revision, um die neuesten Daten einfügen zu k?nnen. Ein etwas vernachl?ssigtes Ergebnis besteht darin, da\ dabei die Sch?tzungen der zugrunde liegenden Parameter beeinflu\t werden. Es ist das Ziel der vorliegenden Abhandlung, die zeitlichen Ver?nderungen der Parameterschatzungen eines makro-?konomischen Modells, die aufgrund verschiedener Methoden gewonnen wurden, zu untersuchen. Die Studie kommt zu dem Ergebnis, da\ die Sch?tzwerte, die aufgrund einer Sequenzanalyse erzielt wurden, ausgepr?gten Trends folgen und da\ darüber hinaus die zeitlichen Perioden, die aufgrund alternativer Sch?tzmethoden bestimmt wurden, oft erheblich voneinander abweichen.

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Résumé Analyse des changements successifs dans l’estimation des paramètres d’un modèle de l’économie des Etats-Unis. — Le pronostic à l’aide de modèles économétriques exige une révision continuelle en vue d’incorporer les données les plus récentes. Le résultat, quelque peu négligé, en est que les estimations des param\ `etres de base en sont affectées. Cet article cherche à analyser les changements successifs des paramètres d’un modèle macro-économique — estimations qui furent trouvées par de différentes méthodes. L’étude arrive à la conclusion que les estimations trouvées par une analyse séquentielle suivent des tendances prononcées et, en outre, que les périodes trouvées par de différentes méthodes diffèrent souvent sensiblement l’une de l’autre.

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Resumen Análisis de las variaciones de paráetres estimados en el tiempo, utilizando un modelo de la economía de los Estados Unidos. — Proyecciones hechas con la ayuda de modelos econométricos requieren un revisión permanente con el fin de poder introducir los datos más recientes. El problems que entonces surge, y que nos recibe siempre la debida atenci?n, consiste en que las estimaciones de los paramé-tras reaccionen de alguna mariera. El objetivo del presente trabajo es analizar la variación de estas estimaciones en el tiempo; para ello se emplea un modelo macroecon?mico estimado por diversos métodos. El resultado del anàlisis es que las estimaciones conseguidas por medio de un análisis de secuencia muestran claramente un trend; ademas se puede ver que los resultados obtenidos a través de métodos de estimaci?n alternatives difieren a menudo de modo sustancial los unos de los otros.

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Riassunto Esami delle modificazioni di stime di parametro nel decorso del tempo in un modello dell’economia degli Stati Uniti. — Prognosi in base a modelli econometrici richiedono una revisione costante per poter inserire i dati più recenti. Un risultato un po’ trascurato consiste nel fatto che con ci? sono influenzate le stime dei parametri che sono alla base. E obiettivo del presente studio di esaminare le modificazioni temporali delle stime dei parametri di un modello macroeconomico che fu ottenuto in base a metodi diversi. Lo studio perviene al risultato che i valori di stima che furono raggiunti in base ad un’analisi di sequenza seguono ?trend? marcati e che oltre a ciò i periodi temporali che furono determinati in base a metodi di stima alternativi spesso differiscono in maniera rilevante.

     

DATA REVISIONS AND FORECASTING ACCURACY: AN ECONOMETRIC ANALYSIS BASED ON PRELIMINARY AND REVISED NATIONAL ACCOUNTING ESTIMATES*

This paper entails an investigation of the effects of data revisions on forecasting accuracy, through use of preliminary and revised national accounting data compiled by the United Nations. A small model was estimated for each of fourteen countries and ex post“forecasts” generated for each country and each year of the period 1957–1964, using first preliminary and then revised data. A prior analysis of the data revisions indicated a strong and widespread tendency for the preliminary estimates to understate both levels and year-to-year changes. This is consistent with the findings of other studies. Two sets of forecasts obtained from the reduced form of the model were considered in relation to “actual” levels and changes, obtained from the revised data, and also in relation to each other. A strong downward bias was observed in the forecasts of levels based on preliminary data, and a weaker one in the forecasts of changes. The forecast discrepancies for different variables were found to be significantly correlated. The results suggest that a tendency toward understatement in preliminary data may account in part for the general tendency toward understatement in forecasts noted in other studies.     

Will African Agriculture Survive Climate Change?

Measurement of the likely magnitude of the economic impact ofclimate change on African agriculture has been a challenge.Using data from a survey of more than 9,000 farmers across 11African countries, a cross-sectional approach estimates howfarm net revenues are affected by climate change compared withcurrent mean temperature. Revenues fall with warming for drylandcrops (temperature elasticity of –1.9) and livestock (–5.4),whereas revenues rise for irrigated crops (elasticity of 0.5),which are located in relatively cool parts of Africa and arebuffered by irrigation from the effects of warming. At first,warming has little net aggregate effect as the gains for irrigatedcrops offset the losses for dryland crops and livestock. Warming,however, will likely reduce dryland farm income immedia-tely.The final effects will also depend on changes in precipitation,because revenues from all farm types increase with precipitation.Because irrigated farms are less sensitive to climate, wherewater is available, irrigation is a practical adaptation toclimate change in Africa.