Data Collection
Agricultural Production Survey: June 2006 (Final)
Methodology
Period-specific information
**Survey information**
This release contains the final results from the 2006 Agricultural Production Survey. This sample survey is part of an ongoing programme of agricultural production statistics conducted in partnership with the Ministry of Agriculture and Forestry.
The eligible population for the 2006 Agricultural Production Survey was 65,000 enterprises.
**2006 questionnaire changes**
Sale or lease of entire farm - These questions were modified to make it easier for survey participants to provide the information required.
Grain and seed crops - This question was expanded to include vegetable seed growing as a separate item.
Grazing - The questions relating to "grazing of livestock owned by someone else" and "grazing of your livestock elsewhere" were expanded to include separate items for dairy cows and heifers aged over 1 but under 2 years, rising 1-year-old heifers and all other dairy cattle. These questions also asked survey participants to specify the main types of other dairy cattle, beef cattle, sheep and all other livestock being grazed on or off the farm. These changes improved reconciliation between the grazing and main livestock questions.
**Sample design**
For the 2006 Agricultural Production Survey, a stratified sample design was used to select a sample from the population. In selecting this sample, the population was stratified by regional council area, ANZSIC group, and size group. The size groups were determined as follows:
- For those businesses that responded to the 2002, 2003, 2004 or 2005 agricultural collections, production data was used to form size groups. The variables used to determine size covered a range of livestock and cropping variables. Typically, three size groups were formed: small, medium and large.
- For new businesses, or those businesses that did not respond to the 2002, 2003, 2004 or 2005 agricultural collections, a random sample was taken. Annualised GST and land area (where available) were investigated for forming size groups, but these measures did not prove useful, so this group was not stratified further.
The 2006 Agriculture Production Survey has a sample size of 30,600.
**2006 Sampling error and imputation levels**
The following table shows the sampling error and imputation levels for the 2006 Agricultural Production Survey:
| Description | Relative sampling errors at 95% confidence interval (%) | % of total estimate imputed |
|---|---|---|
| Ewe hoggets put to ram | 4 | 13 |
| Breeding ewes (2-tooth and older) put to ram | 2 | 13 |
| Total sheep | 2 | 12 |
| Lambs born to ewe hoggets | 5 | 13 |
| Lambs born to ewes | 2 | 13 |
| Total lambs | 2 | 13 |
| Dairy cows and heifers, in milk or calf | 3 | 15 |
| Total dairy cattle | 3 | 15 |
| Calves born alive to dairy heifers/cows | 4 | 15 |
| Beef cows and heifers in calf (age 1–2 years) | 6 | 12 |
| Beef cows and heifers in calf (aged 2 years and over) | 3 | 13 |
| Total beef cattle | 2 | 13 |
| Calves born alive to beef heifers/cows | 3 | 13 |
| Female deer mated | 3 | 12 |
| Total deer | 4 | 12 |
| Fawns born on the farm | 3 | 12 |
| Area of new forestry plantings (hectares) | 23 | 13 |
| Area of forestry replantings (hectares) | 2 | 2 |
| Exotic timber harvested (hectares) | 2 | 2 |
| Exotic timber harvested (cubic metres) | 2 | 2 |
| Wheat tonnage harvested | 18 | 10 |
| Wheat area harvested (hectares) | 19 | 10 |
| Barley tonnage harvested | 12 | 10 |
| Barley area harvested (hectares) | 12 | 10 |
| Oat grain tonnage harvested | 30 | 10 |
| Oat grain area harvested (hectares) | 28 | 11 |
| Maize grain tonnage harvested | 19 | 12 |
| Maize grain area harvested (hectares) | 20 | 12 |
| Other cereal grains tonnage harvested | 36 | 26 |
| Other cereal grains area harvested (hectares) | 36 | 26 |
The sampling error in this table shows that, for example, there is a 95 percent chance that the rue number of sheep in New Zealand at 30 June 2006 lies within 2 percent of the published estimate. This does not take into account non-sampling error.
**Response rates**
The estimated proportion of eligible businesses responding to the 2006 Agricultural Production Survey is 86 percent. These businesses represent 88 percent of the total estimated value of agricultural operations.
General information
**About the estimates**
Figures in this release are rounded. All percentages in this release are calculated using unrounded figures. The figures from the Agricultural Production Survey may differ from those produced from other sources, such as the National Exotic Forestry Description Survey produced by the Ministry for Primary Industries, the Stock Number Survey from Beef and Lamb New Zealand Limited, and Dairy Statistics from Livestock Improvement Corporation Limited. These surveys use different survey frames and designs.
**Population frame**
The Agricultural Production Survey includes all units identified on Statistics New Zealand's Business Frame as having agricultural activity. The Business Frame is a list of businesses in New Zealand, based on their registration for goods and services tax (GST) with Inland Revenue. It should be noted that the compulsory registration level for GST is $40,000, so there is a partial and unquantifiable coverage of units below this level.
**Survey population**
The survey population for the Agricultural Production Survey is all businesses engaged in 'agricultural production activity' (including livestock, cropping, horticulture, and forestry), or which owned land that was intended for agricultural activity. The survey population includes businesses engaged in agriculture or forestry production as a secondary activity.
**Industries in scope**
The survey population specifically includes businesses classified to the following ANZSIC06 codes:
- A01 Agriculture
- A0301 Forestry (excluding native forestry).
It also includes parts of:
- L671200 Non-residential property operators
- M691000 Scientific research services (agriculture-related research that involves land holding (excluding universities))
- P802300 Combined primary and secondary education (agricultural high school operation)
- P802400 Special school education (special needs education involving agricultural production activity)
- P810200 Higher education (agriculture-related research undertaken by universities that involves land holding)
- R912100 Horse and dog racing administration and track operation
- R912900 Other horse and dog racing activities (racehorse training and racing stables operations)
- R892200 Nature reserves and conservation parks operation.
The survey population specifically excludes:
- A019300 Beekeeping
- part of A019900 Other livestock farming nec (worm farming, pet breeding, dog breeding, cat breeding, bird breeding (except poultry, game birds, ostriches, and emus))
- A017100 Poultry meat (except growers who also produce eggs for human consumption).
**Population changes**
For the 2002 Census, we sourced the population from the Business Frame and the Inland Revenue Client Register. We checked these sources against industry lists and AgriBase to ensure all large units were included in the population.
After the 2002 Census, we used the Business Frame for the censuses and surveys.
**Survey content changes**
Users should note that there have been changes to the core information collected in agricultural production collections.
Since 1981, agricultural production collections have collected information on livestock and arable farming, horticulture and forestry with the following exceptions:
1999 – the survey collected information on livestock and arable farming only
2000 – the survey collected horticulture production information only
2004 and 2006 – the surveys collected information on livestock and arable farming, and forestry (horticulture production information was not collected).
**Past questionnaire changes**
Forestry
The reference date for forestry production estimates changed to 31 March in the 2005 Agricultural production Survey. For the 2002 Census, and the 2003 and 2004 surveys, the year end date was 31 December. Agricultural Production collections prior to the 2002 Agricultural Production Census used the 30 June year end date. This change was made to allow the forestry section of the Agricultural Production Survey to align more closely with the National Exotic Forest Description Survey (NEFD) run by the Ministry of Agriculture and Forestry.
Fawns
In 2005 and 2006, data relates to fawns born on the farm that were alive at four months. This change takes into account industry recommendations. In 2003 and 2004, data related to fawns weaned on the farm. In 2002, data related to fawns born on the farm.
Deer
Users should note that 2004, 2005 and 2006 deer figures are not directly comparable with 2002 and 2003 figures. Improvements made to the questions about deer in the 2004, 2005 and 2006 surveys have resulted in improved estimates for deer. While it is not possible to quantify the exact extent of the previous undercoverage, Statistics NZ estimates an undercount of about 70,000 deer at 30 June 2002 and 50,000 at 30 June 2003. The deer question was expanded in the 2005 and 2006 surveys to include a more detailed sex/age breakdown.
**Reliability of survey estimates**
Errors are divided into two classes: sampling error and non-sampling error.
Sampling error arises from selecting a sample of businesses rather than taking a complete enumeration, and is not applicable when there is a census. Estimates for the 2006 survey, as for the 1995, 1996, 1999, 2003, 2004 and 2005 surveys, are subject to sampling error. The 1994 and 2002 Agricultural Production Censuses and the 2000 Horticultural Production Survey are not subject to sampling error.
Non-sampling error arises from biases in the patterns of response and non-response, inaccuracies in reporting by respondents, and errors in the recording and classification of data. Statistics NZ adopts procedures to detect and minimise these types of errors, but they may still occur and are not easy to quantify.
**Imputation**
Values are imputed for farmers and foresters who do not return a completed questionnaire. Imputation involves replacing missing items with values based on other information available.
The method of imputation used is random 'hot deck' imputation.
A proportion of non-respondents are estimated as ineligible for imputation. The remaining non-respondents are grouped into imputation cells based on regional council area, ANZSIC06 group, and previous years' production data. Each non-respondent is then randomly assigned to a respondent in the same imputation cell, and the farm production data of the respondent is copied across to the non-respondent.
To improve the imputation process, respondents with uncharacteristically high levels of agricultural activity are removed from their respective imputation cells. It is unlikely that any of the non-respondents would have similar characteristics to them.
**Confidentiality**
Data collected and information contained in this release must conform to the provisions of the Statistics Act 1975. This requires that published information maintains the confidentiality of individual respondents. Figures affected by these provisions have been suppressed and are denoted by 'C'.
**Quality suppression**
Data with high sample errors or imputation levels have been suppressed and are indicated by an 'S'.
**More information**
For more information, follow the link from the technical notes of this release on the Statistics NZ website.
**Liability**
While all care and diligence has been used in processing, analysing, and extracting data and information in this publication, Statistics NZ gives no warranty it is error-free and will not be liable for any loss or damage suffered by the use directly, or indirectly, of the information in this publication.
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