The Use of Alternative Predictions in Long-Term Inference into the Future (with special Reference to Water Demand)

This paper, the eighth in the IIASA water demand series, reports on the use of alternative predictions in long-term inference into the future, with special reference made to forecasting water demands. Following an outline of several standard approaches for determining the values of explanatory variables of an econometric model, a new method of building "optimistic" and "pessimistic" predicitons is presented. The interval defined by these two predictions provides information on what can be expected when extreme cases are excluded from consideration. Based on this material, the concept of alternative predictions is introduced and illustrated by several examples that refer explicitly to water demand forecasting. This approach can be used for assessing the future values of explanatory variables of the econometric model as well as for final prediction of the future values of the endogenous variable. The paper ends by presenting a method of building alternative predictions that minimizes the sum of expected losses due to incorrect prediction and of costs due to the initiation of some actions on the assumption that an alternative prediction will prove correct. Practical applicability of the proposed methods is demonstrated and recommendations are made as to how they could be extended further

Basic Problems of Long-Term Inference into the Future

Water resource systems have been an important part of resources and environment related research at IIASA since its inception. As demands for water increase relative to supply, the intensity and efficiency of water resources management must be developed further. This in turn requires an increase in the degree of detail and sophistication of the analysis, including economic, social and environmental evaluation of water resources development alternatives aided by application of mathematical modeling techniques, to generate inputs for planning, design, and operational decisions. During the year of 1978 it was decided that parallel to the continuation of demand studies, an attempt would be made to integrate the results of our studies on water demands with water supply considerations. This new task was named "Regional Water Management" (Task 1, Resources and Environment Area). Although this paper does not refer explicitly to water resources, it is concerned with the problems of primary importance to water resources planning. In several countries very significant capital investments are being made and contemplated for the future for water supply projects of increasing size. The purpose of these projects is to satisfy future water demands which often are estimated (predicted) on the basis of statistically derived demand relationships. The paper examines some of the major problems and difficulties involved in the use of statistically derived relationships for long-term inference into the future

DEMP-1: Some Counterfactual Simulation Results

This is the second IIASA Working Paper on DEMP-1 -- the Demoeconometric Model of Poland. This model seeks to examine the process of economic growth and its impact on the time-behavior of demographic variables, such as birth, death, and migration rates, and population totals in urban and rural areas. The paper presents the reduced form of the model and illustrates some of its uses: counterfactual simulation results and direct multiplier analysis. The counterfactual simulation was based on two scenarios, one extrapolating to the 1970's the moderate growth experienced in the 1960's and one assuming from the start (since 1960) a high rate of growth, as was observed in the period 1971-1976. The analysis of direct multipliers shows that trends and sharp shifts of economic policy, which occur from time to time because of changes in relevant economic and administrative decisions, play an especially large role in the impact of economics on demographic factors

A Demoeconometric Model of Poland and its Application to Counterfactual Simulations

This paper presents the results of modeling the impact of economic factors in the Polish economy on basic demographic phenomena and in turn, the way these phenomena act on various economic variables, especially those pertaining to employment levels. After a brief exposition of the main characteristic features of the Polish economy, the author explains the method by which the equations of the model are built and presents the estimated structural form of the model. The results are used to obtain the reduced form which is later used for a number of counterfactural simulations. These simulations are based on two scenarios. One of them assumes that during the period covered by sample data, i.e., 1960-1976, Poland was experiencing steady but moderate economic growth. The second scenario was built on the assumption of fast economic growth, coupled with a strong rise in the standard of living. When the counterfactual simulations were performed it was found that the two different economic policies would have had a substantially different impact on such demographic variables as birth rates, death rates, and migrations from rural to urban areas, as well as on employment levels in the three sectors of the national economy considered, namely nonagricultural productive activities, agriculture, and services

Some Comments on the Estimation of Demand Relations for Poland

Understanding the nature and dimensions of the world food problem and the policies available to alleviate it has been the focal point of the IIASA Food and Agriculture Program since it began in 1977. National food systems are highly interdependent, and yet the major policy options exist at the national level. Therefore, to explore these options, it is necessary both to develop policy models for national economies and to link them together by trade and capital transfers. For greater realism the models in this scheme are being kept descriptive rather than normative. In the end it is proposed to link models to twenty countries, which together account for nearly 80 per cent of important agricultural attributes such as area, production, population, exports, imports and so on. In the course of the work on the development of models of centrally planned economies, the difficulties of estimating parameters of consumer behavior in such economies where consumer markets cannot be assumed to be in equilibrium become apparent. Since the understanding of consumer behavior is critically important in formulating plans and designing policies that facilitate the realization of plans, we have explored alternative approaches to this problem. This paper proposes one possible approach to estimating consumer demand relations

A Demoeconometric Model of Poland: DEMP 1

This paper presents a demoeconometric model of Poland, i.e., a model that tries to explain the growth mechanism of the economy not only by analyzing economic or technological factors, but also by making use of a number of demographic variables. The behavior of some important demographic phenomena is, in turn, presented as being a function of economic factors. A general view of the model is given, as well as the endogenous and the predetermined variables used. The model concentrates on five blocks of phenomena: 1) employment, 2) investments, 3) national income formation, 4) consumption, and 5) demography. In its present form the model may be used to analyze the quantitative relations between the variables chosen, to compute counterfactual simulations, and to make predictions on future behavior

Mucosal immune responses following intestinal nematode infection.

In most natural environments, the large majority of mammals harbour parasitic helminths that often live as adults within the intestine for prolonged periods (1-2 years). Although these organisms have been eradicated to a large extent within westernized human populations, those living within rural areas of developing countries continue to suffer from high infection rates. Indeed, recent estimates indicate that approximately 2.5 billion people worldwide, mainly children, currently suffer from infection with intestinal helminths (also known as geohelminths and soil-transmitted helminths) . Paradoxically, the eradication of helminths is thought to contribute to the increased incidence of autoimmune diseases and allergy observed in developed countries. In this review, we will summarize our current understanding of host-helminth interactions at the mucosal surface that result in parasite expulsion or permit the establishment of chronic infections with luminal dwelling adult worms. We will also provide insight into the adaptive immune mechanisms that provide immune protection against re-infection with helminth larvae, a process that is likely to be key to the future development of successful vaccination strategies. Lastly, the contribution of helminths to immune modulation and particularly to the treatment of allergy and inflammatory bowel disease will be discussed

An enzyme-linked immunosorbent assay for diagnostic detection of Taenia saginata copro-antigens in humans

An immunodiagnostic sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection of soluble Taenia saginata antigens in stool samples (copro-antigens) of infected humans, using affinity-purified polyclonal antibodies obtained from rabbits hyperimmunized with excretory/secretory antigens derived from T. saginata maintained in vitro. Investigation of operating characteristics showed very low cross-reactivity with crude antigens from helminths other than Taenia, including Dipylidium caninum and Diphyllobothrium latum. The specificity of the assay was 95% when testing stool samples from 100 persons who were either infected with Ascaris lumbricoides, Trichuris trichiura, hookworms, Enterobius vermicularis or Hymenolepis nana, or who had no intestinal helminthosis detected. Analysis of diagnostic sensitivity demonstrated that in 85% of 34 samples from 23 untreated persons with intestinal T. saginata infection (selected by previous proglottid and/or egg detection) copro-antigens were detected by the T. saginata ELISA. In the same samples, Taenia eggs were detected in 62%. Only 41% of the samples reacted positively in a heterologous T. hydatigena ELISA. Post-treatment control revealed a high concentration of T. saginata copro-antigens for 1-4 d after administration of niclosamide or praziquantel, and negative values 9-17 d after treatment. The Taenia copro-antigens remained detectable by ELISA even after storage of untreated faeces at 25 °C for at least 5

Prediction of preterm birth with and without preeclampsia using mid-pregnancy immune and growth-related molecular factors and maternal characteristics.

OBJECTIVE:To evaluate if mid-pregnancy immune and growth-related molecular factors predict preterm birth (PTB) with and without (±) preeclampsia. STUDY DESIGN:Included were 400 women with singleton deliveries in California in 2009-2010 (200 PTB and 200 term) divided into training and testing samples at a 2:1 ratio. Sixty-three markers were tested in 15-20 serum samples using multiplex technology. Linear discriminate analysis was used to create a discriminate function. Model performance was assessed using area under the receiver operating characteristic curve (AUC). RESULTS:Twenty-five serum biomarkers along with maternal age <34 years and poverty status identified >80% of women with PTB ± preeclampsia with best performance in women with preterm preeclampsia (AUC = 0.889, 95% confidence interval (0.822-0.959) training; 0.883 (0.804-0.963) testing). CONCLUSION:Together with maternal age and poverty status, mid-pregnancy immune and growth factors reliably identified most women who went on to have a PTB ± preeclampsia