The education and professional experience of demographers: results of an international survey

This paper presents findings relating to the education, disciplinary background and professional experience of 634 demographers responding to a mainly internet-based survey carried out in 1999-2000. Two thirds of the survey respondents have some training in demography, and virtually all have studied some other subject also. Academic backgrounds are quite varied, with sociology (broadly defined), economics, mathematics/statistics and geography being the most common. Findings presented relate to: the combinations of disciplines studied, current practise of discipline of origin, interdisciplinary activity, place of education, education abroad, current and past sectors of employment and time-use. Differentials by age, gender and region of residence or birth are considered

Why we measure period fertility

Four reasons for measuring period fertility are distinguished: to explain fertility time trends, to anticipate future fertility, to construct theoretical models and to communicate with non-specialist audiences. The paper argues that not all measures are suitable for each purpose, and that tempo adjustment may be appropriate for some objectives but not others. In particular, it is argued that genuine timing effects do not bias or distort measures of period fertility as dependent variable. Several different concepts of bias or distortion are identified in relation to period fertility measures. Synthetic cohort indicators are a source of confusion since they conflate measurement and forecasting. Anticipating future fertility is more akin to forecasting than to measurement. Greater clarity about concepts and measures in the fertility arena could be achieved by a stronger emphasis on validation. Period incidence and occurrence-exposure rates have a straightforward interpretation. More complex period fertility measures are meaningful only if a direct or indirect criterion can be specified against which to evaluate them. Their performance against that criterion is what establishes them as valid or useful

The age difference at marriage in England and Wales: a century of patterns and trends

In the last 100 years the mean age difference at marriage in England and Wales has fluctuated in the range 2–3 years, but without exhibiting any long-run trend. Nevertheless, an age gap of 2–3 years is not typical. A 1-year gap is the most common in recent years and there is a good deal of variation between couples. Marriage partners are closer in age than would be predicted if men and women were matched at random by age. There is little evidence that the age difference is governed by strong social norms. Some explanations for diversity and change in the age difference are discussed

Cohabitation and marriage in Britain since the 1970s

The article presents an overview of trends in cohabitation and marriage in Britain over several decades, using a consistent set of retrospective histories from the General Household Survey 1979–2007. Time-trends are presented, for men and women, of: the experience of different types of partnership by specified ages, the frequency of premarital cohabitation, the average time spent in different types of partnership, the timing of life course transitions, and the outcome of cohabitation and marriage at the fifth and tenth anniversaries

Does Postponement Explain the Trend to Later Childbearing in France?

Fertility rates in most developed societies have been declining at younger ages and rising at older ages. This phenomenon is widely referred to as reflecting the postponement of fertility. But is this an accurate description? The present paper considers whether recent changes in the age-pattern of childbearing in France can be described as postponement. The statistical features of time series of rates are distinguished from the underlying behavioural process generating them. Criteria for the presence of postponement are proposed. In the absence of detailed, longitudinal information on intentions, the occurrence or otherwise of postponement is assessed by indirect means. Some evidence is found consistent with fertility postponement in recent decades. However, it cannot be interpreted causally, and so cannot be used either to explain recent trends or to anticipate future trends. Much more detailed evidence is required to establish the existence of postponement in the behavioural sense than is generally assumed.

The trend to later childbearing: is there evidence of postponement?

Fertility rates in most developed societies have been declining at younger ages and rising at older ages. This phenomenon is widely referred to as reflecting the postponement of fertility. But is this an accurate description? The paper considers whether recent changes in the age-pattern of childbearing in France can be described as postponement. The statistical features of time series of rates are distinguished from the underlying behavioural process generating these. Criteria for the presence of postponement are proposed. In the absence of detailed, longitudinal information on intentions, the occurrence or otherwise of postponement is assessed by indirect means. Some evidence is found consistent with fertility postponement in recent decades. However, it cannot be interpreted causally, and so cannot be used either to explain recent trends or to anticipate future trends. Much more detailed evidence is required to establish the existence of postonement in the behavioural sense than is generally assumed

Tempo and the TFR

The paper proposes that whether period indicators are biased by timing effects depends on the objective of measurement. Several kinds of bias in the TFR are identified. Five reasons for measuring period fertility are distinguished: to explain fertility time trends, to anticipate future prospects, to describe trends, to provide input parameters for formal models, and to communicate with non-specialist audiences. Genuine timing effects are not biasing where period fertility is the explanandum, but are distorting where the aim is to estimate cohort fertility. Synthetic measures such as the TFR have a number of known defects. Alternatives to the TFR are available, and seem a more defensible solution to current problems than tempo adjustment. Tempo adjustment could be more fruitfully considered a form of modelling rather than empirical measurement. The measurement of period fertility could benefit by a more statistical approach and less reliance on indicators requiring stable assumptions.<br/

Five reasons for measuring period fertility

Five reasons for measuring period fertility are distinguished: to describe fertility time trends, to explain these, to anticipate future population prospects, to provide input parameters for formal models, and to communicate with non-specialist audiences. The paper argues that not all measures are suitable for each purpose, and that tempo adjustment may be appropriate for some objectives but not others. In particular, it is argued that genuine timing effects do not bias or distort measures of period fertility as dependent variable. Several different concepts of bias or distortion are identified in relation to period fertility measures. Synthetic cohort indicators are a source of confusion since they conflate measurement and forecasting. Anticipating future fertility is more akin to forecasting than to measurement. Greater clarity about concepts and measures in the fertility arena could be achieved by a stronger emphasis on validation. Period incidence and occurrence-exposure rates have a straightforward interpretation. More complex period fertility measures are meaningful only if a direct or indirect criterion can be specified against which to evaluate them. Their performance against that criterion is what establishes them as valid or useful. Discussion of tempo adjustment and allied issues in demographic measurement might profit from the development of a theory of measurement in demography, comparable to the axiomatic systems devised in e.g. physics, psychology and some areas of economics such as price index theory