The United Nations Statistics Division defines a household as a residence unit that consists of one or more persons who make common provision for food and other essentials for living. Unlike a family, which comprises only persons related through blood, adoption, or marriage, a household may include members who are not related. While different concepts of household are sometimes adopted, the United Nations definition is widely used for both data collection and demographic research.
The household is one of the most important human socioeconomic institutions, with functions that vary both across regions and over time. In many historical populations, a household was not only a residence group but also a socioeconomic unit within which production, consumption, reproduction, early childhood socialization, and many other activities took place. Many of these functions are still important in contemporary households. It is this multifaceted character that makes the household an appealing subject of study to many social scientists.
Household composition is a description of the household according to certain characteristics of its membership, such as age, relationship to the head of the household, and number of marital pairs or nuclear families it contains. (A nuclear family is a married couple, or a couple–or a single parent–together with unmarried offspring.) In addition to indicating the household structure, these descriptions are useful in revealing why such residence groups are formed in a particular way, how they function in the society, and their socioeconomic consequences.
The investigation of household composition generally uses data from population censuses or sample surveys. In historical studies, census-type materials such as lists of inhabitants or household registers are frequently used. Family reconstitution data and genealogical records shed light on potential residential patterns, but they do not usually include information on household composition.
Historical research on household composition progressed rapidly in the second half of the twentieth century, and studies show remarkable variations in household composition prior to the twentieth century. As pointed out by John Hajnal and others, households in northwest Europe (encompassing the British Isles, the Low countries, German-speaking areas, northern France, and Scandinavia including Iceland but excluding Finland) were generally between four and five persons in size, included in most cases a single nuclear family, and rarely any more distant relatives, but might have non-relatives present. In eastern and southern Europe, in contrast, scholars have noted that it was common for the newly married to live with the parents of one of the spouses, and an appreciably higher proportion of households consisted of two or more married couples. In some Asian populations (e.g. China, India, Japan) the proportion of complex households–defined as those with one nuclear family plus other relatives or other nuclear families–was also considerably higher than in northern and western Europe.
Significant changes in household composition have taken place in many developed countries since the late nineteenth century. As a general trend, the household has become simpler in structure and smaller in size. In England, for example, between 1891 and 1981 the proportion of complex households fell from above 15 percent to less than 5 percent, and the proportion of single-person households increased from 7 percent to 22 percent. During the later part of this period, nonmarital co-habitation also rose rapidly: by the late 1980s, nearly a quarter of women aged 20 to 24 lived in such households. In Sweden, proportions of single-person households and of households comprising cohabiting couples were even higher. Similar changes were observed in most developed countries. The result of these trends has been a continual shrinkage in the average size of households, from around five persons per household at the end of the nineteenth century to two to three persons per household at the end of the twentieth century.
The transition in household composition has been directly related to the following factors. First, there has been a considerable change in people's reproductive behavior. During the twentieth century, in particular its second half, the proportion of women remaining childless increased and the level of fertility of those having children decreased. In many developed countries, the total fertility rate fell to well below the replacement level. As a result, the average number of children present in a household is much lower than in the past. Second, there has been a significant change in people's attitude toward marriage. Since the mid-twentieth century, non-marital cohabitation has been increasingly accepted by society. Divorce has become far more common, and there is less stigma attached to remaining single. All these changes contribute to the increase in single-person households, one-parent households, and consensual unions. Thirdly, there is also a noticeable decrease in propensities for coresidence between parents and their married children, and between nuclear family members and their distant relatives. Before the twentieth century, the proportion of complex households formed through such relationships was around 10 to 20 percent in England, and higher than this in many other countries; living arrangements of this kind were rare by the beginning of the twenty-first century. This change is partly a result of higher income levels and, among the elderly, improved health, allowing more people to live alone and independently when such an arrangement is preferred.
Similar trends have been found in some less-developed countries. In China and South Korea, for example, household size has also become smaller and its structure simpler in recent years. But the change in household composition in most less-developed countries has been slow and the pattern of change less clear. John Bongaarts found that in the 1990s, household size and composition in many of these countries were markedly different from those recorded in the developed countries, but similar to those observed in the second half of the nineteenth century in Europe and North America. As far as household size is concerned, the world is still very diverse: Average household size ranges from seven persons in Algeria and Oman to just above two persons in Sweden. In most of the less-developed countries, the average size of households is still between four and seven persons.
Examining household composition can reveal much about a society, but its limitations should not be ignored. The composition of a household identified from cross-sectional data is only a snapshot taken at a particular point in the process of household development. The dynamics of this process need to be studied to understand the household formation system and its outcomes. Furthermore, households are not socially isolated but exist within broader networks of kin and other social ties. Although the household is a fundamental unit, many socioeconomic activities take place in a wider context (e.g., a lineage or a group of kin-related households). Knowledge of these wider networks is important for a full understanding of household formation and composition.
Bongaarts, John. 2001. "Household Size and Composition in the Developing World in the 1990s." Population Studies 55: 263–279.
Hajnal, John. 1983. "Two Kinds of Pre-Industrial Household Formation Systems." In Family Forms in Historic Europe, ed. Richard Wall, Jean Robin, and Peter Laslett. Cambridge, Eng.: Cambridge University Press.
Laslett, Peter. 1983. "Family and Household as Work Group and Kin Group: Areas of Traditional Europe Compared." In Family Forms in Historic Europe, ed. Richard Wall, Jean Robin, and Peter Laslett. Cambridge, Eng.: Cambridge University Press.
Lesthaeghe, Ron. 1995. "The Second Demographic Transition in Western Countries: An Interpretation." In Gender and Change in Industrialized Countries, ed. Karen Oppenheim Mason, and An-Margritt Jensen. Oxford: Clarendon Press.
United Nations. 1998. Principles and Recommendations for Population and Housing Census (Revision 1). New York: United Nations.
Wall, Richard. 2001. "The Transformation of the European Family across the Centuries." In Family History Revisited: Comparative Perspectives, ed. Richard Wall, Tamara Hareven, and Joseph Ehmer. Newark: University of Delaware Press.