Major obstacles to control of irregular migrations: prerequisites to policy

This paper examines 3 basic obstacles thwarting all attempts to reduce irregular migration. The 1st, rather well known and analyzed, underscores the dependency of all regulation of migratory flows on the system of economic and political relations between developed and developing countries. The 2nd obstacle resides in the persistance and growth of subsequent dependent irregular migration. This obstacle also reveals the relative autonomy of population movements compared with the employment situation in the labor market. The 3rd generally ignored obstacle is the role played by migration itself, particularly the discriminatory status of foreign workers in the labor market, in producing irregular migration.     

Perceived morbidity, utilisation of health services and factors affecting it in a rural area

A survey of perceived morbidity was carried out in rural population in eight villages and four wards of Saoner town, covering a total population of 8,876. The nature of illness was assessed by weekly visits to the families. History regarding treatment taken for disease and its source was taken. The overall incidence of perceived morbidity was 176.35 spells of sickness per 1000 population per month. Health care agency was contacted for 36.7 per cent spells of sickness. Utilisation of health services was found to be affected significantly by factors like age (chi 2 = 138.36), literacy (chi 2 = 14.123), type of occupation (chi 2 = 433.74), nature of illness (chi 2 = 83.578) and accessibility of health services. A health behaviour model of the population has also been discussed in this paper.     

On some characteristics of China's population--analysis of the ten percent sampling tabulation of the 1982 third national population census

Advance results from the 1982 census of China are presented based on a 10 percent sample. Sections are included on age distribution, centenarians, marriage patterns, educational status, and the labor force. Several characteristics of China's population are described in this article, based on a 10% sampling tabulation of the production teams and resident groups of the whole country. Data are included for 100,380,000 people. The proportion of the population aged 0-14 is 33.60%, which marks a decline from figures in the 1964 census (40%). This decline is attributed to family planning and population control efforts. The median age is 22.91 years, which is 2.71 years older than that in the 1964 census. The % of the population aged 15-64 rose from 55.7% in 1964 to 61.5%. The dependency ratio dropped from 79.4% (1964) to 62.6%. There were 3,765 centenarians as of July, 1982; the overwhelming majority live in villages, and most (94.77%) are illiterate or semiliterate. The number of female centenarians is 2.4 times that of males. Marriages are comparatively stable in China. 63.6% of the population aged 15 and over are married, and .59% are divorced. The % of the population remaining single after age 50 is .21% for females, 2.97% for males. The average 1st marriage age is 22.80 years for females and 25.49 years for males. 60.35% of the people have had primary education or above; .44% are college graduates. In 1964, 33.58% of the population illiterate or semiliterate. At present, among people aged 12 and over, 31.90% are illiterate or semiliterate. The rural illiteracy rate is more than twice the urban rate. 51.94% of the total population is employed. Of these, 92.08% are engaged in manual labor. Males exceed females in all professions and occupations. The median age of the employed population is 30.84 years. The level of education among the employed is relatively low: 28.26% are illiterate or semiliterate, and 34.35% have had primary education only.     

Solving the part families problem in discrete-parts manufacture by simulated annealing

In the production planning and control of discrete-parts manufacture, aggregation of parts into families, on the basis of similarity, is carried out to ease both long-horizon planning and short-horizon scheduling. Additional advantages are related to those of group technology (GT), such as simplifying the flow of parts and tools and reducing both set-up and production costs. The problem of formally forming part families is presented and discussed. Previous work is reviewed and assessed. Two solution approaches, one based on a location model, the other on simulated annealing, are presented and compared along with test results. The location formulation, which results in an integer programming model solved by Lagrangian relaxation, proved capable of producing solutions of excellent quality, but only for relatively small problem instances. In contrast, simulated annealing, which is a general heuristic approach to combinatorial optimization, produced solutions of comparable quality and could handle realistically large problem instances. However, careful design of the simulated annealing algorithm is crucially important. An effective design is presented.     

SPC—a team effort for process improvement across four Area Control Centres

This paper describes an innovative application of statistical process control to the online remote control of the UK's gas transportation networks. The gas industry went through a number of changes in ownership, regulation, access to networks, organization and management culture in the 1990s. The application of SPC was motivated by these changes along with the desire to apply the best industrial statistics theory to practical problems. The work was initiated by a studentship, with the technology gradually being transferred to the industry. The combined efforts of control engineers and statisticians helped develop a novel SPC system. Having set up the control limits, a system was devised to automatically update and publish the control charts on a daily basis. The charts and an associated discussion forum are available to both managers and control engineers throughout the country at their desktop PCs. The paper describes methods of involving people to design first-class systems to achieve continual process improvement. It describes how the traditional benefits of SPC can be realized in a 'distal team working', and 'soft systems', context of four Area Control Centres, controlling a system delivering two thirds of the UK's energy needs.     

SPC as a tool for creating a successful business measurement framework

Many companies are trying to get to the bottom of what their main objectives are and what their business should be doing. The new Six Sigma approach concentrates on clarifying business strategy and making sure that everything relates to company objectives. It is vital to clarify each part of the business in such a way that everyone can understand the causes of variation that can lead to improvements in processes and performance. This paper describes a situation where the full implementation of SPC methodology has made possible a visual and widely appreciated summary of the performance of one important aspect of the business. The major part of the work was identifying the core objectives and deciding how to encapsulate each of them in one or more suitable measurements. The next step was to review the practicalities of obtaining the measurements and their reliability and representativeness. Finally, the measurements were presented in chart form and the more traditional steps of SPC analysis were commenced. Data from fast changing business environments are prone to many different problems, such as the short previous span of typical data, strange distributions and other uncertainties. Issues surrounding these and the eventual extraction of a meaningful set of information will be discussed in the paper. The measurement framework has proved very useful and, from an initial circulation of a handful of people, it now forms an important part of an information process that provides responsible managers with valuable control information. The measurement framework is kept fresh and vital by constant review and modifications. Improved electronic data collection and dissemination of the report has proved very important.     

Diagnostic checks for discrete data regression models using posterior predictive simulations

Model checking with discrete data regressions can be difficult because the usual methods such as residual plots have complicated reference distributions that depend on the parameters in the model. Posterior predictive checks have been proposed as a Bayesian way to average the results of goodness-of-fit tests in the presence of uncertainty in estimation of the parameters. We try this approach using a variety of discrepancy variables for generalized linear models fitted to a historical data set on behavioural learning. We then discuss the general applicability of our findings in the context of a recent applied example on which we have worked. We find that the following discrepancy variables work well, in the sense of being easy to interpret and sensitive to important model failures: structured displays of the entire data set, general discrepancy variables based on plots of binned or smoothed residuals versus predictors and specific discrepancy variables created on the basis of the particular concerns arising in an application. Plots of binned residuals are especially easy to use because their predictive distributions under the model are sufficiently simple that model checks can often be made implicitly. The following discrepancy variables did not work well: scatterplots of latent residuals defined from an underlying continuous model and quantile–quantile plots of these residuals.     

Two ways of modelling overdispersion in non-normal data

For non-normal data assumed to have distributions, such as the Poisson distribution, which have an a priori dispersion parameter, there are two ways of modelling overdispersion: by a quasi-likelihood approach or with a random-effect model. The two approaches yield different variance functions for the response, which may be distinguishable if adequate data are available. The epilepsy data of Thall and Vail and the fabric data of Bissell are used to exemplify the ideas.