National Family and Household Projections: 2001 (base) - 2021

Alternative projection series

Nine alternative series of family and household projections have been produced by Statistics New Zealand using different combinations of fertility, mortality, migration and living arrangement type rate assumptions. These series are neither predictions nor forecasts. The projections provide an indication of possible future changes in the number, size and growth rate of families and households. These projections have as a base the estimated resident population, estimated families and estimated households at 30 June 2001, and cover the period 2002–2021. They are the first set of national family and household projections to be produced using a 'propensity' method, superseding the 1996-base New Zealand household projections which used a 'household head' method.

The nine alternative series are derived from combinations of three national population projection series (series 3, 4 and 5) and three variants of living arrangement type rates (A, B and C). The three national population projection series incorporate the same fertility and mortality assumptions but have different migration assumptions:

1. The total fertility rate will decrease to 1.85 births per woman by 2011 and then remain constant.
2. Life expectancy at birth will increase by four years between 2001 and 2021, to 80.3 years for males and 84.8 years for females.
3. Long-term annual net migration of zero for projection series 3, 5,000 for projection series 4 and 10,000 for projection series 5.

The three variants of living arrangement type rates are:

1. Rates will remain constant at 2001 levels.
2. Rates will change linearly between 2001 and 2021 based on an assessment of observed trends between 1986 and 2001, and likely future trends, by sex and single-year of age.
3. Rates will change linearly between 2001 and 2021 according to the linear trend observed between 1986 and 2001, by sex and single-year of age.

At the time of this release, projection series 4B is considered the most suitable for assessing future family and household changes. The following analysis is based on series 4B, unless otherwise stated.

Families

The number of families is projected to increase 230,000 or 22 percent between 2001 and 2021, from 1.05 million to 1.28 million. This compares with population growth of 16 percent over the same period. A family, as defined here, consists of a couple, with or without child(ren), or one parent with child(ren), usually living together in a household.

Projection series 5A, which assumes long-term annual net migration of 10,000 and living arrangement type rates remaining constant at 2001 levels, yields the highest number of families in 2021 of 1.31 million, an increase of 260,000 or 25 percent on the 2001 figure. Projection series 3C, which assumes long-term annual net migration of zero and living arrangement type rates changing linearly according to the linear trend between 1986 and 2001, projects the lowest number of families in 2021 of 1.20 million.

Family type

Under projection series 4B, the number of couple without children families is expected to increase substantially, from 407,000 in 2001 to 614,000 in 2021. One-parent families are also expected to increase during the projection period, from 198,000 to 251,000, but two-parent families are expected to decrease from 446,000 to 418,000. The projected changes reflect recent trends:

1. Fewer couples having children.
2. More single parenting because of increasing numbers of separations and divorces, increasing rates of childbearing outside of couple relationships, and more complex shared care arrangements with parents residing in different households.
3. An increasingly older population age structure.

Two-parent families were the most common family type in 2001, accounting for 42 percent of all families. By 2006, they are projected to be surpassed by couple without children families as the most common family type. Couple without children families are expected to account for 48 percent of all families in 2021, while two-parent families will account for 33 percent. One-parent families are projected to account for the remaining 20 percent of families in 2021, up slightly from 19 percent in 2001.

Families with dependent children

As children can be of any age, it is useful to distinguish families with dependent children (people aged under 18 years and not in full-time employment) from families with older children. In 2001, about 84 and 77 percent of two-parent and one-parent families, respectively, contained dependent children. Assuming these proportions increase slightly during the projection period, the number of families with dependent children is projected to increase from 525,000 in 2001 to 551,000 in 2010, and then remain steady for the rest of the projection period.

Within these families, the number of one-parent families with dependent children is projected to increase throughout the projection period, from 153,000 in 2001 to 196,000 in 2021. In contrast, after an initial increase from 372,000 in 2001 to 380,000 in 2005, two-parent families with dependent children are projected to decrease to 355,000 in 2021. Two-parent families will account for 64 percent of families with dependent children in 2021, down from 71 percent in 2001. .

Households

The number of households is projected to increase by 380,000 or 26 percent between 2001 and 2021, from 1.44 million to 1.82 million. This is faster growth than that of families (22 percent) and the population (16 percent) over this period, reflecting the trend towards smaller average household size and more one-person households. A household is defined as one person usually living alone, or two or more people usually living together and sharing facilities (eg eating facilities, cooking facilities, bathroom and toilet facilities, a living area) in a private dwelling.

Projection series 5C, which assumes long-term annual net migration of 10,000 and living arrangement type rates changing linearly according to the linear trend between 1986 and 2001, yields the highest number of households in 2021 of 1.87 million, an increase of 420,000 or 29 percent. Projection series 3B, which assumes long-term annual net migration of zero and living arrangement type rates changing linearly based on an assessment of trends between 1986 and 2001 and likely future trends, gives the lowest number of households in 2021 of 1.77 million.

Household type

Family households are projected to increase by 210,000 or 21 percent, from 1.02 million in 2001 to 1.23 million in 2021. However, family households will account for a smaller share of all households in 2021 (68 percent) compared with 2001 (71 percent).

Over the same period, one-person households are expected to increase by 149,000 or 45 percent, from 333,000 to 482,000. This is mainly due to the increasing population at older ages. Of all people in one-person households, 47 percent are projected to be aged 65 years and over in 2021 compared with 42 percent in 2001. One-person households will account for 27 percent of households in 2021, compared with 23 percent in 2001.

The number of other multiperson households (households containing more than one person, but not containing a family) is expected to increase by 14,000 or 16 percent, from 88,000 in 2001 to 102,000 in 2021. They will continue to account for about 6 percent of all households. About half of the population in other multiperson households is aged 18–28 years.

Average household size

The average size of households is projected to decrease from 2.6 people in 2001 to 2.4 people in 2021. This continues the steady decline of recent decades. In 1951 there were 3.7 people per household, but by 1981 this had fallen to 3.0 people per household.

The trend towards smaller average household size is due to an increase in the number of one-person households and a decrease in the average size of family households. The latter is projected to decline from 3.2 people in 2001 to 2.9 people in 2021, reflecting changes in both the type and size of families. In 2021, there are expected to be more couple without children families and one-parent families, but fewer two-parent families. Couple without children families, by definition, contain two people. One-parent families contained an average of 2.7 people in 2001 – by 2021, the average will be about 2.5 people. Two-parent families are generally larger, averaging 4.0 people in 2001 – by 2021, the average will be about 3.9 people per family.

Living arrangement types

The 2001-base family and household projections were produced by allocating people to one of eleven living arrangement types. Assumptions have been made about the future propensity of people to live in each living arrangement type, by age and sex. Projection series 4B, which applies the variant B living arrangement type rates to the 2001-base national population projection series 4, gives one scenario for the living arrangements of the population during the 2001–2021 period.

The number of partners in couple without children families is projected to grow fastest, to 1.23 million in 2021 compared with 810,000 in 2001, an increase of 410,000 or 51 percent. The two main contributing factors to this increase are (a) declining fertility, with fewer couples having children, and (b) increasing population in the ages where people are most likely to be living as couples without children (ages 50–90 years). In 2021, 71 percent of partners in couples without children are projected to be aged 50 years and over, compared with 63 percent in 2001. Almost one-third will be aged 65 years and over in 2021.

The number of parents in one-parent families is expected to increase by 26 percent between 2001 and 2021, while partners/parents in two-parent families will decline by 6 percent. An 11 percent increase is projected in the number of children in one-parent families over the projection period, while the number of children in two-parent families is projected to fall by 10 percent. Of children in one-parent families, the number aged under 15 years is projected to increase by 7 percent, from 230,000 to 247,000, while the number aged 15 years and over is projected to increase by 20 percent, from 105,000 to 126,000. In 2001, 31 percent of children in one-parent families were aged 15 years and over.

The ageing population is expected to lead to an increase of 24,000 or 32 percent in the number of people living in non-private dwellings (which includes retirement homes), from 76,000 in 2001 to 100,000 in 2021. Almost 40 percent of people living in non-private dwellings are projected to be aged 80 years and over in 2021, compared with 28 percent in 2001. These figures assume a decrease in the proportion of older people living in non-private dwellings, due to improvements in life expectancy and well-being in the older ages. If the proportion of people living in non-private dwellings by age and sex was to remain at 2001 levels (series 4A), people in non-private dwellings could number 110,000 in 2021, an increase of 34,000 or 45 percent compared with 2001.