### Alternative projection series

This release contains 2006-base family and household projections for New Zealand. The projections have as a base the estimated resident population, estimated families and estimated households at 30 June 2006, and cover the period to 2031 at one-year intervals. These projections are neither predictions nor forecasts. They provide an indication of possible future changes in the number and composition of families and households.

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. Couples include opposite-sex and same-sex couples. A household is defined as one person usually living alone, or two or more people usually living together and sharing facilities (for example, eating facilities, cooking facilities, bathroom and toilet facilities, a living area) in a private dwelling.

Six alternative series have been produced from combinations of three population series (series 1, 5 and 9) and two variants of living arrangement type rates (A and B). Series 1, 5 and 9 of the 2006-base national population projections released in October 2007 are used. Series 1 assumes low fertility, high mortality and low migration; series 5 assumes medium fertility, medium mortality and medium migration; and series 9 assumes high fertility, low mortality and high migration.

The two variants of living arrangement type rates are:

- Rates will remain constant at 2006 levels.
- Rates will change linearly between 2006 and 2031 based on an assessment of observed trends between 1986 and 2006, and likely future trends, by sex and single-year of age.

Variant B is the preferred variant, because it has been formulated to produce demographically plausible results by assessing both historical trends and likely future trends. For comparison, variant A is formulated solely on the basis of historical rates.

Each family and household projection series is denoted by the population projection series and variant of living arrangement type rates. For example, series 5B denotes that variant 'B' living arrangement type rates have been applied to population projection series 5. Further details of the assumptions are contained in the Technical notes.

### Which projection series should I use?

The six alternative series have been produced to illustrate a range of possible scenarios. Users can make their own judgement as to which projection series is/are most suitable for their purposes. However, at the time of release, Statistics New Zealand considers projection series 5B the most suitable for assessing future family and household changes. The following analysis is based on series 5B unless otherwise stated.

### What has changed from the previous 2001-base projections?

These national family and household projections incorporate information from the 2006 Census of Population and Dwellings, and national population projections (released 24 October 2007).

Compared with the previous 2004-base national population projections (released 16 December 2004), mid-range series 5 of the 2006-base national population projections assumes:

- A base population at 30 June 2006 of 4.18 million. This is 58,000 or 1.4 percent higher than the 4.13 million projected from the 2004-base national population projections (series 5), mainly because observed net migration was higher than assumed. Net migration between 30 June 2001 and 2006 was an estimated 161,000, based on estimated population change less natural increase (births minus deaths), compared with the medium migration variant of 104,000 in the 2004-base projections.
- An average total fertility rate of 2.09 births per woman during 2007–11, dropping to 2.00 during 2012–16; 1.94 during 2017–21; 1.91 during 2022–26; and 1.90 thereafter. By comparison, the previous 2004-base projections assumed the average total fertility rate dropped from 1.95 during 2007–11 to 1.88 in 2012–16 and 1.85 thereafter. These higher fertility levels incorporate the recent rise in the total fertility rate, from about 1.9 in the year ended June 2002, to 2.0 in the year ended June 2006, and to 2.1 in the year ended June 2007.
- Net migration of 46,000 in the five years to 30 June 2011 and 50,000 in each subsequent five-year period. By comparison, the previous 2004-base projections assumed net migration of 38,000 in the five years to 30 June 2011, and 50,000 in each subsequent five-year period.
- Life expectancy at birth will increase to 82.5 years for males and 86.2 years for females in 2031. By comparison, the previous 2004-base projections assumed life expectancy at birth of 82.1 years for males and 85.9 years for females in 2031.

The projection assumptions for the national family and household projections incorporate these changes. The combined effect of these changes is that the New Zealand population is expected to reach 4.39 million in 2011; 4.59 million in 2016; 4.77 million in 2021; 4.94 million in 2026; and 5.09 million in 2031 (series 5, 2006-base national population projections). By comparison, under series 5 of the 2004-base national population projections, the New Zealand population was expected to reach 4.29 million in 2011; 4.45 million in 2016; 4.59 million in 2021; 4.73 million in 2026; and 4.85 million in 2031. Differences in the projected age-sex structure of the population will also cause differences in the number, size and type of families and households.

### Families

Under series 5B, the number of families is projected to increase by 269,000 (23 percent) between 2006 and 2031, from 1.17 million to 1.44 million. Because of the changing age structure of the population, this will exceed the population growth of 22 percent over the same period. Like population growth, growth in the number of families is expected to slow over the projection period – from an average of 13,000 a year in 2007–11 to 8,000 a year in 2027–31.

Series 9A, which assumes high fertility, low mortality, high migration and living arrangement type rates constant at 2006 levels, projects the highest number of families in 2031, with an increase of 350,000 (30 percent) to 1.52 million in 2031. The smallest increase in the number of families is given by series 1B, with an increase of 211,000 (18 percent) to 1.38 million in 2031. This series assumes low fertility, high mortality, low migration and living arrangement type rates changing linearly between 2006 and 2031 based on the observed trend between 1986 and 2006 and likely future trends

### Family type

Couple without children families will account for the majority of growth in the number of families. There are projected to be 263,000 (56 percent) more couple without children families in 2031 than in 2006, with an increase from 468,000 to 730,000. Couple without children families include (a) couples who will never have children, (b) couples who will have children in the future, and (c) couples whose children have left the parental home. Growth in (c) is expected to be the most significant, as the large number of people born after World War II reach ages 50 years and over. An increasing proportion of couples in (a) is also assumed to contribute to the increasing number of couple without children families, but to a lesser extent.

The number of one-parent families is projected to increase by 63,000 (29 percent), from 219,000 in 2006 to 282,000 in 2031. This increase is because of population growth, changes in population age structure, and an assumed higher rate of single parenting. The latter is due to 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. If the rate of single parenting was to remain at the 2006 level, series 5A (which assumes medium fertility, medium mortality, high migration and living arrangement type rates constant at 2006 levels) shows that the number of one-parent families would increase by 38,000 (17 percent), to 257,000 in 2031. It should be noted that children in families can be of any age, and can include a mature child living with older parent(s).

The number of two-parent families is projected to decrease after 2006, because of the continuing trends towards single parenting and fewer couples having children. Under series 5B, the number of two-parent families is projected to decrease from 481,000 in 2006 to 425,000 by 2031. If living arrangement type rates were to remain at 2006 levels, series 5A projects a 10 percent increase in the number of two-parent families between 2006 and 2031, to 529,000.

Two-parent families were the most common family type in 2006, accounting for 41 percent of all families. Couple without children families accounted for 40 percent of all families in 2006. Under series 5B, couple without children families are projected to surpass two-parent families as the most common family type by 2008. Couple without children families will account for 51 percent of all families by 2031, while two-parent families will account for 30 percent. One-parent families are projected to account for 20 percent of all families in 2031, up from 19 percent in 2006.

### 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 2006, about 83 percent of two-parent families and 75 percent of one-parent families contained dependent children. Assuming these proportions remain constant during the projection period, the number of families with dependent children is projected to increase slightly from 565,000 in 2006 to 566,000 in 2031. Growth will slow in the first six years of the projection period (2007–12), with an increase of 4,000 families with dependent children, followed by a decrease of 3,000 during 2013–24, before an increase of 500 from 2025–31. The slowing growth mainly reflects the projected trends in the total number of two-parent families discussed in the previous section ('Family type').

Within these families, the number of two-parent families with dependent children is projected to decrease from 400,000 in 2006 to 353,000 by 2031. In contrast, the number of one-parent families with dependent children will increase throughout the projection period, from 165,000 in 2006 to 212,000 in 2031. Two-parent families will account for 62 percent of families with dependent children in 2031, down from 71 percent in 2006.

### Households

Under series 5B, the number of households is projected to increase by 535,000 (34 percent), from 1.55 million in 2006 to 2.09 million in 2031. This growth is faster than that of families (23 percent) and the population (22 percent) over this period, reflecting the trend towards smaller average household size and the increasing number of non-family households.

The number of households is projected to increase under all six projection series. The largest increase is projected under series 9B, where the number of households will increase by 620,000 (40 percent) to 2.18 million in 2031. This series assumes high fertility, low mortality, high migration and living arrangement type rates changing linearly between 2006 and 2031 based on an assessment of observed trends between 1986 and 2006, and likely future trends. The smallest increase is projected under series 1A, which assumes low fertility, high mortality, low migration and living arrangement type rates constant at 2006 levels. Under this series, the number of households will increase by 412,000 (27 percent) over the projection period, reaching 1.96 million by 2031.

### Household type

One-person households are projected to be the fastest-growing household type, increasing by 257,000 (71 percent) from 363,000 in 2006 to 619,000 in 2031. One-person households will account for 30 percent of all households in 2031, up from 23 percent in 2006. The growth in this household type will be mainly due to the increasing number of people at older ages, with 80 percent of the growth occurring among those aged 55 years and over. Of all people in one-person households, 67 percent are projected to be aged 55 years and over in 2031, compared with 49 percent in 2006.

Family households are projected to increase by 259,000 (23 percent), from 1.12 million in 2006 to 1.38 million in 2031. However, because of the faster increase in the number of one-person households, family households will account for a smaller share of all households in 2031 (66 percent) than in 2006 (72 percent). Family households can contain more than one family, or other people living with (but not in) a family. It is estimated that there was an average of 1.04 families per family household in 2006.

The number of other multi-person households (households containing more than one person, but not containing a family) is expected to increase from 68,000 in 2006 to 88,000 in 2031 – an increase of 20,000 or 29 percent. Other multi-person households will account for 4 percent of all households throughout the projection period. People aged 18–29 years will continue to account for about half of all people in other multi-person households.

### Average family and household size

The average size of households is projected to slowly decline between 2006 and 2031, from 2.6 to 2.4 people per household. This continues the decline seen in recent decades, with the average household size falling from 3.7 people in 1951 and 3.0 people in 1981.

The projected decrease in average household size is due to the increasing proportion of one-person households and a decrease in the average size of family households. The latter is projected to fall from 3.2 people in 2006 to 3.0 people in 2031, reflecting changes in both the type and size of families. By 2031, there are expected to be more couple without children families and one-parent families, but fewer two-parent families. Two-parent families are generally larger, with an average size of 4.0 people in 2006 increasing slightly to 4.1 people by 2031. Couple without children families, by definition, contain two people. One-parent families contained an average of 2.6 people throughout the projection period.

Average Size of Families and Households | ||||||||

Series 5B | ||||||||

Family type | Household type | |||||||

Year at 30 June |
Couple without children | Two- parent | One- parent | All families | Family(1) | Other multi-person | One- person | All households |

Average size (people) | ||||||||

2006(base) | 2.0 | 4.0 | 2.6 | 2.9 | 3.2 | 2.6 | 1.0 | 2.6 |

2011 | 2.0 | 4.0 | 2.6 | 2.9 | 3.1 | 2.6 | 1.0 | 2.6 |

2016 | 2.0 | 4.0 | 2.6 | 2.8 | 3.1 | 2.6 | 1.0 | 2.5 |

2021 | 2.0 | 4.1 | 2.6 | 2.8 | 3.1 | 2.6 | 1.0 | 2.5 |

2026 | 2.0 | 4.1 | 2.6 | 2.8 | 3.0 | 2.6 | 1.0 | 2.4 |

2031 | 2.0 | 4.1 | 2.6 | 2.7 | 3.0 | 2.6 | 1.0 | 2.4 |

(1) The average size of family households is larger than the average size of families because family households can contain more than one family and other people living with (but not in) a family. |

### Living arrangement types

The 2006-base national family and household projections were produced by allocating people to one of 11 living arrangement types. Assumptions have been made about the future propensity of people to live in each living arrangement type, by age and sex. The projected number of families and households are derived from the projected population by living arrangement type.

Under series 5B, the living arrangement type projected to experience the fastest growth is one-person households. The number of people in this living arrangement type is projected to increase by 71 percent from 363,000 in 2006 to 619,000 in 2031. The main factor behind this growth is the result of the movement of the large number of people born during the 1950s to early 1970s into the older ages. Twelve percent of the population will be living alone in 2031, compared with 9 percent in 2006.

Population ageing is also the main reason for the large projected increases in the numbers of people living in non-private dwellings (which includes retirement homes), up 51 percent between 2006 and 2031. The number of people aged 80 years and over living in a non-private dwelling is projected to double between 2006 and 2031, from 23,000 to 49,000. This increase is despite a small assumed 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.

The number of parents in one-parent families is projected to increase by 29 percent between 2006 and 2031. This increase is due to population growth, changes in population age structure and a continuing increase in the rate of single parenting. However, because of a decline in the average number of births per woman, the number of children in one-parent families will increase at a slower rate, up 23 percent between 2006 and 2031. An increase in the rate of single parenting and fewer couples having children will mean there are 12 percent fewer parents in two-parent families in 2031 than in 2006. The number of children in two-parent families will fall by 6 percent over the same period.

For technical information contact:

Rino Adair or Simon Pang

Christchurch 03 964 8700 **Email:** demography@stats.govt.nz