Family demography is a subfield of demography and is the study of the changing nature of intergenerational and gender ties that bind individuals into households and family units. The core of family demography uses basic demo graphic information collected about household members, including the numbers of members, their relationships to each other, and each per son’s sex, age, and marital status, to describe the composition of families and households. Com position describes the structure of families and households: the set of statuses and associated roles that are important for the functioning of society. American families and households have diverse and complex structures. For example, households can contain married couples, cohabiting couples, single mothers, children, grandparents, other relatives (e.g., brothers, sisters, or in laws), roommates, or simply one person living alone. Family composition is the result of demographic processes or family related events such as marriage, divorce, and fertility or childbearing. Changes in the timing, number, and sequences of these events transform family and household composition. Family demographers aggregate the composition and processes of individual families into larger units (e.g., nations, states, counties, neighborhoods) to examine family change in societies and other units. They aggregate them separately by other social and economic groups (e.g., racial and ethnic groups, poor families, immigrants) and by countries to examine family variation. Thus, family demographers study family change and variation to understand both individual and societal behavior.
Several theoretical strands are influential in interpreting family change and variation in family demographic research. They include (second) demographic transition theory, the life course perspective, household and family decision making theories, biodemographic interactions, and the focus on culture and context.
The bedrock of demographic data analysis on family change is descriptive cross sectional and trend analysis of family structures and processes, most often with census or survey data, although increasingly qualitative methods are also used. The field of demography has its own toolkit full of measures and methods that are suited to studying family change. Measures of age and age related processes are fundamental. Change is understood as reflecting age, period, or cohort processes or effects; explanations of change emphasize the aging of the population (or life course change of individuals), broad, sweeping societal or time period effects, and/or the replacement of older cohorts by successively younger ones with different life experiences. An indispensable measure in family demography is the rate: the number of people experiencing the event out of the population ‘‘at risk’’ of experiencing that event. Another important tool for examining family change is decomposition, in which family change is empirically separated into two components: the proportion of change attributable to shifts in population composition versus that part that is due to change in the likelihood that some family event occurs. However, family demography has increasingly moved toward explaining family change and variation. In the last three decades, a number of panel surveys and various labor force and educational cohort studies have been developed. These studies include many more ‘‘explanatory’’ variables and provide prospective sequencing data that are better suited to inferring causality.
Common Definitions
The core of family demography continues to be based on concepts developed by the US Census Bureau. A household, as defined by the US Census Bureau, consists of one or more people who occupy a house, apartment, or other residential unit (but not ‘‘group quarters’’ such as dormitories). One of the people who owns or rents the residence is designated the house holder. The householder is said to maintain the household. For the purposes of examining family and household composition using census data, two types of households have been defined: family and non-family. A family house hold has at least two members related by blood, marriage, or adoption, one of whom is the householder. Families consist of all related people in a family household. Families can be maintained by married couples with or without children or by a man or woman with children and no spouse in the home. A non-family house hold can either be a person living alone or a householder living only with non-relatives. Family units within family or non-family households that do not include the householder are subfamilies. Subfamilies include either a married couple, with or without children, or a parent–child pair. A related subfamily is related to the householder, whereas an unrelated sub family is not. Family groups are family households plus all related and unrelated subfamilies. For example, a family household that is maintained by a grandmother and contains her daughter and her daughter’s daughter has two family groups. Children include sons and daughters by birth, stepchildren, and adopted children of the householder regardless of the child’s age or marital status. Own children are a subset of children and identify the householder or family reference person as a parent in the household, family, or subgroup – they are usually defined as never married children under the age of 18.
Family and Household Composition and Living Arrangements
Changes in the number and types of households depend on population growth, shifts in the age composition of the population, and decisions individuals make about their living arrangements. Demographic trends in marriage, cohabitation, divorce, fertility, and mortality also influence family and household composition. Economic shifts and improvements in the health of the elderly over time can also have an impact.
In the US, families have traditionally accounted for a large majority of all households – as recently as 1940, nine out of ten households were family households. This proportion decreased steadily to 81 percent in 1970 and by 2003 family households made up only 68 per cent of all households, with the remaining 32 percent accounted for by non-family living arrangements. Part of the increase in non-family households was due to the growth in one person households – people living alone. The proportion of households containing one person increased from 17 percent in 1970 to 26 percent in 2003.
The increase in non-family households resulted from many social, economic, and demo graphic shifts. A postponement of marriage took place after 1960 leading to a substantial increase in the percentage of young, never married adults and to greater diversity and fluidity in living arrangements in young adulthood. In 1970, 6 percent of women and 9 percent of men aged 30–34 had never married. By 2003, these figures increased to 23 percent and 33 percent, respectively. The delay of marriage means that young adults in 2003 were less likely to be living with their spouses and more likely to be living alone, in a parent’s home, or with roommates, than they were in the past. Thirty one percent of men aged 18–24 lived with their spouses in 1970, for example, while only 9 percent lived with a spouse in 2003. A similar drop occurred for women: from 45 percent in 1970 to 16 percent in 2003. As a declining share of young adults chose married life, a greater share lived on their own, with roommates, or cohabited with an unmarried partner. In 1970, 15 percent of women and 13 percent of men were living in these arrangements compared with 38 percent and 37 per cent, respectively, in 2003.
The delay in marriage coincided with an increase in cohabitation and these trends also decreased the proportion of married couple families and increased the proportion of non-family households. Unmarried couple (cohabiting) households have grown dramatically since 1970 and in 2003 numbered 4.6 million, or over 4 percent of households. Cohabitation historically has been most likely to occur before a first marriage, but, more recently, cohabitation has been replacing remarriage after divorce occurs. Researchers have offered several explanations for the rapid increase in cohabitation, including increased uncertainty about the stability of marriage, the erosion of norms against cohabitation and sexual relations outside of marriage, the wider availability of reliable birth control, and increased individualism and secularization. Some have argued that cohabitation allows a couple to experience the benefits of an intimate relationship without committing to marriage. If a cohabiting relationship isn’t successful, one can simply move out; if a marriage is not successful, one suffers through a sometimes lengthy and messy divorce.
Significant improvements in the health and economic wellbeing of the elderly over the period have increased the life expectancy and the quality of life of both men and women. This means that elderly men and women are increasingly able to maintain their own homes.
Not only has this augmented the number of households, but also the fact that women continue to outlive men by a significant number of years has led to a greater number and proportion of one person non family households. The proportion of women 65 years and over who live alone grew from 34 percent in 1970 to 40 percent in 2003.
Households and families have become smaller over time, with the most profound changes occurring at the extremes – the largest and smallest households. Between 1970 and 2003 the share of households with five or more people decreased from 21 percent to 10 percent. During the same period, the share of households with only one or two people increased from 46 percent to 60 percent. Another mea sure of household size is the average number of members in the household. Between 1970 and 2003 the average number of people per house hold declined from 3.1 to 2.6.
Changes in fertility, marriage, divorce, and mortality all contributed to the shrinkage of American families and households. Between 1970 and 2003, births to married women declined sharply while births to unmarried women increased. These two trends decreased the proportion of two parent families and increased the proportion of one parent families, which also tend to have fewer children. The cumulative effect of these trends was to shrink family and household size. Increases in divorce also reduced the size of households and families; divorce generally separates one house hold into two smaller households. Meanwhile, the proportion of divorced people increased about fourfold from 2 percent to 8 percent for men and from 3 percent to 11 percent for women from 1970 to 2003.
The delay in marriage and improvements in the mortality and health of the elderly increased one person households, thereby decreasing the average family and household size.
Other aspects of the composition of families changed as well. The number of families maintained by people with no spouse at home increased rapidly from 1970 to 2003. Single mother families grew by 147 percent from 5.5 million in 1970 to 13.6 million in 2003. Single father families grew even more over the same period, tripling from 1.2 million to 4.7 million. By contrast, married couple families grew from 44.1 million to 50.7 million over the same period – only a 15 percent increase. These differential increases shifted the composition of family households from married couple to single mother and single father families. In 1970, married couples maintained 89 percent of family households, but by 2003 this proportion had declined to 72 percent.
Several demographic trends have affected the shift from two parent to one parent families. A larger proportion of births occurred to unmarried women in 1990 compared with 1970, increasing the proportion of never married parents. The delay of marriage also augmented the risk of a non-marital birth, because adults were single for more years. In addition, the growth in divorce among couples with children increased the proportion of unmarried parents.
Most of the decline in family households reflects the decrease in the share of married couple households with children. In 2003, 48 percent of families contained own children compared with 56 percent in 1970. These changes reflect several demographic trends, including the delay of childbearing, the decline in the number of children people have, the delay of marriage, and the aging of the population. Due to the trend toward delayed marriage and childbearing, younger families were more likely to be childless in 2003 than in 1970. For example, in 1970, 94 percent of women aged 30–34 had been married at least once; of them, only 12 percent were childless. In 2002–3, only 77 percent of women aged 30–34 had ever been married; of them, 19 percent were childless. Thus, fewer women in these prime childbearing ages had ever been married in 1990 and nearly twice as many of them were childless (reflecting primarily a delay in childbearing, but also a delay in marriage).
Change in family and household structure began slowly in the 1960s, just as society was embarking on some of the most radical social changes in US history, and the leading edge of the huge baby boom generation was reaching adulthood. The steepest decline in the share of family households was in the 1970s when the first baby boomers entered their twenties. By the 1980s, change was still occurring, but at a much less rapid pace. By the mid-1990s, house hold composition reached relative equilibrium, where it has been since.
Family Change in Other Industrialized Countries
The changes in family that occurred in the US have also occurred throughout most industrialized countries, for many of the same reasons. In most European countries marriage rates have been declining since the late 1960s and early 1970s. Since the 1980s, marriage rates have continued to decline, but at a slower pace. Europeans are also postponing marriage. For example, the median age at first marriage in Sweden was 25 in 1975, but increased to 29 by 1995. The increase was even greater in Denmark: from 23 in 1975 to 29 in 1995. Although women tend to marry earlier in most other Northern and Central European countries, the average age of marriage increased from 1975 to 1995 and now stands at 26 or above in these countries.
As in the US, a rise in cohabitation has contributed to the decline and postponement of marriage. In the 1960s in Sweden and Denmark, cohabitation as a prelude to or an alternative to marriage began to rise. By the 1970s, this type of cohabitation began to rise in other countries. Postmarital cohabitation has also increased.
Women in other industrialized countries are postponing births and having more non-marital births. For example, in most European countries, the age specific fertility rates declined for women under 25 and rose substantially for women aged 30 and over in the 1980s. Non marital births in Scandinavia grew about 20 percent between 1975 to 1988. In Northern Europe, Australia, and New Zealand the growth rate was not as large – in the single digits for all countries except for the United Kingdom (16 percent) and France (18 percent).
Social Demography of the Family
Early family demographic studies documented change and variation in fertility, marriage, households and families, and living arrangements, with each of these areas typically studied in isolation. Growing diversity in the timing, number, and sequencing of family events led researchers in the US and other industrialized countries to study the interaction of these events (e.g., non-marital childbearing) and to incorporate other events (e.g., cohabitation) into family demography to provide a more accurate accounting of family change and variation. Family demography has also expanded to examine the causes and consequences of family change and variation, including the social and economic context in which it occurs. This change has led many demographers who study the family to refer to the field as social demography of the family. It has also increased the number of disciplines that have adopted the demographic perspective. Historically, the majority of family demographers had training in sociology and a substantial minority had training in economics. More researchers in the fields of anthropology, child development, family studies, genetics, geography, medicine, psychology, and public health have come to employ the concepts and tools of family demography.
Several key changes in the family occurring in developed countries in the second half of the twentieth century have expanded the borders of family demography beyond the traditional measures of family composition, processes, and living arrangements. Historically, family demography only included the study of marriage, remarriage, and divorce. However, changing union (marriage and cohabitation) formation and dissolution, low fertility, increases in non-marital fertility and a growing diversity of family structures, changing intergenerational relations, and increases in women’s paid work have made it necessary for family demographers to study a broad set of processes to adequately characterize and explain family change and variation and to explore the consequences of these changes.
The rise of cohabitation and the delay and decline in marriage have prompted family demographers to examine cohabitation. Cohabitation, marriage, divorce, and childbearing are entwined in complicated ways. Cohabitation increasingly precedes marriage, is often an alternative to remarriage after separation and divorce, and, in several European countries, has become a long term substitute for marriage. Intimate Union Formation and Dissolution Tracking and explaining the increase in cohabiting couples, both heterosexual and same sex, and examining the consequences of cohabitation for adults and children require not only a better understanding of cohabitation, but also a better understanding of marriage; the meaning, value, and nature of both of these relationships are poorly understood in contemporary developed economies.
A second area of family change of increasing interest is explaining low fertility in industrialized economies. Fertility is a core focus of family demography, but until relatively recently most research focused on high fertility in developing regions of the world. The rapid decline in fertility in all parts of the developing world has shifted attention away from high fertility and toward the very low fertility levels of Southern and Eastern Europe and Japan. Most of these countries have fertility levels far below the 2.1 children per woman needed to replace the population. Explanations for these low levels of fertility include changing normative, social, and economic contexts, particularly women’s changing work and family roles.
Third, recent increases in childrearing within cohabiting and other non-marital unions have also heightened the awareness that trends in childbearing and childrearing cannot be studied independently of union (marriage and cohabitation) formation and dissolution. Whereas timing of entry into marriage, parenthood, and, to a much lesser extent, cohabitation can be distinguished empirically, conceptually and analytically they are intertwined. In the US, where fertility levels remain close to replacement (around two births per woman, on average), the questions of greatest interest are about two distinct fertility behaviors that characterize US fertility trends. On the one hand, both marriage and children are being postponed to older ages among the better educated segments of the population. On the other hand, there seems to be increased willingness to disassociate childbearing from marriage altogether, particularly among less educated, minority groups – to have children relatively early, outside of marriage, and to raise them in environments that will not include two co residential biological parents. Policymakers and researchers seek to better understand the underlying causes of these different behaviors. They are also interested in the consequences for children and men and women of the separation of marriage and childbearing, on the one hand, and the postponement of both, on the other, and how the consequences vary for different groups within the population.
Fourth, the intergenerational family is changing in form – from a pyramid structure with few living grandparents and many children and grandchildren to the beanpole family with more grandparents than parents and, increasingly, more parents than children. Demographically, these changes occur when mortality is low, life expectancy is high, and fertility is relatively low, as in most industrialized countries. Changes in marriage, divorce, and childbearing complicate the intergenerational picture, as financial and care obligations are no longer necessarily dependent on biological or marital ties. In groups where marriage is increasingly fragile, intergenerational ties may supersede nuclear ties in the rearing of children. Researchers are interested in the economic and social consequences of these changes.
Fifth, the steady increase in women’s labor force participation in the US and most other industrialized countries, especially among married women, in the second half of the twentieth century, and the accompanying decline in the one wage earner, two parent family, provides a greatly altered context for understanding and interpreting family demographic trends. The interrelationship between increased female employment and changes in union formation, fertility, cross generation care giving and the gender division of labor in non-market spheres is receiving increased attention in the family demographic literature of both developed and developing economies.
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