Assessing time series models for forecasting international migration : lessons from the United Kingdom

Funding: This work was funded by the Migration Advisory Committee (MAC), UK Home Office, under the Home Office Science contract HOS/14/040, and also supported by the ESRC Centre for Population Change grant ES/K007394/1.Migration is one of the most unpredictable demographic processes. The aim of this article is to provide a blueprint for assessing various possible forecasting approaches in order to help safeguard producers and users of official migration statistics against misguided forecasts. To achieve that, we first evaluate the various existing approaches to modelling and forecasting of international migration flows. Subsequently, we present an empirical comparison of ex post performance of various forecasting methods, applied to international migration to and from the United Kingdom. The overarching goal is to assess the uncertainty of forecasts produced by using different forecasting methods, both in terms of their errors (biases) and calibration of uncertainty. The empirical assessment, comparing the results of various forecasting models against past migration estimates, confirms the intuition about weak predictability of migration, but also highlights varying levels of forecast errors for different migration streams. There is no single forecasting approach that would be well suited for different flows. We therefore recommend adopting a tailored approach to forecasts, and applying a risk management framework to their results, taking into account the levels of uncertainty of the individual flows, as well as the differences in their potential societal impact.Publisher PDFPeer reviewe

Golden Rule of Forecasting: Be Conservative

This article proposes a unifying theory, or the Golden Rule, or forecasting. The Golden Rule of Forecasting is to be conservative. A conservative forecast is consistent with cumulative knowledge about the present and the past. To be conservative, forecasters must seek out and use all knowledge relevant to the problem, including knowledge of methods validated for the situation. Twenty-eight guidelines are logically deduced from the Golden Rule. A review of evidence identified 105 papers with experimental comparisons; 102 support the guidelines. Ignoring a single guideline increased forecast error by more than two-fifths on average. Ignoring the Golden Rule is likely to harm accuracy most when the situation is uncertain and complex, and when bias is likely. Non-experts who use the Golden Rule can identify dubious forecasts quickly and inexpensively. To date, ignorance of research findings, bias, sophisticated statistical procedures, and the proliferation of big data, have led forecasters to violate the Golden Rule. As a result, despite major advances in evidence-based forecasting methods, forecasting practice in many fields has failed to improve over the past half-century

Geothermal Power Generation as Related to Resource Requirements

For the past several years geothermal exploratory work has been conducted in northern Nevada. In conjunction with that effort a proposed 55-MW steam geothermal power plant was considered for initial installation in one of the fields being developed. The characteristics of the geothermal fields under consideration were not firm, with data indicating widely varying downhole temperatures. Thus, neither the resource nor the plant operating conditions could be set. To assist both the ultimate user of the resource, the utility, and the developer of the geothermal field, a series of parametric sensitivity studies were conducted for the initial evaluation of a field vis-a-vis the power plant. Using downhole temperature as the variable, the amount of brine, brine requirements/kWh, and pounds brine/pound of steam to the turbine were ascertained. This was done over a range of downhole temperatures of from 350F to 475F. The studies illustrate the total interdependence of the geothermal resource and its associated power plant. The selection of geothermal steam power plant design conditions must be related to the field in which the plant is located. The results of the work have proven to be valuable in two major respects: (1) to determine the production required of a particular geothermal field to meet electrical generation output and (2) as field characteristics become firm, operating conditions can be defined for the associated power plant

Erroneous Population Forecasts

World population in the year 2000 was 6.09 billion, according to recent estimates by the United Nations (UN 2005). This number is almost 410 million lower than the year 2000-estimate that the UN expected in 1973. The UN has computed forecasts for the population of the world since the 1950s. Figure 9.1 shows that the calculations made in the 1980s were much closer to the current estimate than those published around 1990. Subsequent forecasts for the world population in 2000 show an irregular pattern: apparently, in 1973 and around 1990 it was rather difficult to predict world population size and much less so in the mid-1980s

Therapeutic ultrasound: a promising future in clinical medicine

Although diagnostic ultrasound is now a multi-billion dollar a year industry, the therapeutic applications of ultrasound were initially thought to have more promise. Indeed, the Fry brothers were performing brain surgery on human patients in the early 1950’s, and with considerable success [1]. However, therapeutic ultrasound has still not yet gained its promising potential. Recently, there has been an enormous resurgence of interest in this topic, and several major projects are underway at various facilities around the world. We shall review our own substantial efforts in this area, with brief discussions of topics in lithotripsy, ultrasound-enhanced drug delivery, and acoustic hemostasis