Impact of developmental variance on behavior of models for insect populations I. Models for populations with unrestricted growth

Summary The concept of developmental variance is discussed with reference to its use in models for insect populations. When included in a model, developmental variance is typically used to describe the variation of developmental periods among individuals. However, its presence in a model can also have indirect impact on survival and fertility schedules. This impact can lead to significant changes in population growth rates and generation times. These relationships between developmental variance and population growth in models are quantified and discussed.     

Dwelling Space: Expectations and the Housing System

The average person-per-room ratio in Australia is low by international standards. But there are marked inequalities in the distribution of dwelling space, and the question is examined of whether the current allocation of dwelling space within the housing system constitutes a social problem on a national scale. The examination is based partly on an analysis of published census data, partly on existing literature, and partly on raw data derived from two recent housing surveys.     

Assessing the impact of planned social change

It is a special characteristic of all modern societies that we consciously decide on and plan projects designed to improve our social systems. It is our universal predicament that our projects do not always have their intended effects. Very probably we all share in the experience that often we cannot tell whether the project had any impact at all, so complex is the flux of historical changes that would have been going on anyway, and so many are the other projects that might be expected to modify the same indicators.It seems inevitable that in most countries this common set of problems, combined with the obvious relevance of social science research procedures, will have generated a methodology and methodological specialists focused on the problem of assessing the impact of planned social change. It is an assumption if this paper that, in spite of differences in the forms of government and approaches to social planning and problem-solving, much of this methodology can be usefully shared — that social project evaluation methodology is one of the fields of science that has enough universality to make scientific sharing mutually beneficial. As a part of this sharing, this paper reports on program impact assessment methodology as it is developing in the United States today.     

Fertility differentials among the tribal groups of Sierra Leone

Abstract Sierra Leone is in a position typical of many African countries regarding accurate information on her basic demographic characteristics. Such vital registration as exists is confined to a small area and there has been only one census of any reliability, that of 1963. Estimates of fertility levels from the age distribution obtained from that enumeration have been made by Dow, the method having been used previously by Van de Walle for Nigeria.