# National Harvest Survey variables

This page describes what information is available on-line and how it can be queried. It also gives guidance on the interpretation of the data.

National Harvest Survey data are offered under three general themes:

## General harvest information

The following options are offered when requesting general harvest data:

- Select a single or multiple continuous years
- Select among three spatial scale resolutions:
- By hunting zone [View map of hunting zones]
- Summarized for a single or all provinces
- Summarized for Canada

- Select by citizenship of hunters:
- Canadians
- Non-canadians (includes mostly residents from the U.S. but also some hunters from other countries)
- All hunters combined

### Description of variables

#### Estimate and Standard Error (SE)

All numerical results tabulated from a survey (e.g., means and proportions) are referred to as estimates. This is because the results are collected from only a sample of the individuals in the population, and a sample is not identical to the total population. A standard error is a measure of the precision of an estimate and describes how much the estimate may differ from the unknown true population value. It itself is an estimate derived from the results of the survey. The smaller the standard error, the more likely the estimate is close to the true value. If the sample size is large (greater then 30), the standard error can be used to derive confidence intervals. As a rule of thumb, the true value has a 95 percent confidence level of being within plus or minus two standard errors of the estimate.

Note that the standard error describes only one source of error in the estimates. It reflects the sampling error caused by selecting only a portion of the population to represent the entire population. Other sources of error exist that may affect the accuracy of the estimate. These include non-response bias, respondents not answering the questions correctly, and data entry errors. The non-sampling error is of unknown magnitude and can only be contained through careful survey design.

When data are summarized for a province or for Canada, estimates are added and the standard error is equal to the square root of the sum of squared standard errors of the individual estimates.

#### Active hunters

The estimated number of hunters who hunted migratory game birds. The variables are ACTIOT (active hunters of non-waterfowl species) and ACTIWF (active hunters of waterfowl species).

#### Potential hunters

The estimated number of hunters who purchased permits and could hunt. These values are obtained from Harvest Questionnaire Survey responses and take into account movement between zones and provinces. Thus, they differ slightly from current permit sales. The variable is POTNTL.

#### Successful hunters

The total number of active hunters who killed and retrieved birds of a particular species or group of species.

Data can be obtained on the following species, which are listed on the harvest questionnaire: ducks (TODUS), geese (TOGOS), coots (COOTS), woodcock (WOODS), snipe (SNIPS), (mourning) doves (DOVES), (band-tailed) pigeons (PIGES), rails (RAILS), and (sandhill) cranes (CRANS). The following groupings are also available: TOWFS (all waterfowl species or all ducks and geese) and TOOTS (all non-waterfowl species).

#### Harvest

The estimated number of birds of a species or group of species that were killed and retrieved by hunters.

Data can be obtained on the following species, which are listed on the harvest questionnaire: all ducks (TODUK), all geese (TOGOK), coots (COOTK), woodcock (WOODK), snipe (SNIPK), (mourning) doves (DOVEK), (band-tailed) pigeons (PIGEK), rails (RAILK), and (sandhill) cranes (CRANK). The following groupings are also available: TOWFK (all waterfowl species or all ducks and geese) and TOOTK (all non-waterfowl species).

#### Days hunting

The total number of days hunters hunted migratory game birds. The following data are available: DAYOT (for non-waterfowl species) and DAYWF (for waterfowl).

## Harvest estimates by waterfowl species

The following options are offered when requesting harvest estimates data:

- Select a single or multiple continuous years
- Select among three spatial scale resolutions:
- By hunting zone for a province [View map of hunting zones]
- Summarized for a single or all provinces
- Summarized for Canada

- Select by species

Here is a list of species common and scientific names (Species codes)

### Description of variables

#### Estimate and Standard Error (SE)

All numerical results tabulated from a survey (e.g., means and proportions) are referred to as estimates. This is because the results are collected from only a sample of the individuals in the population, and a sample is not identical to the total population. A standard error is a measure of the precision of an estimate and describes how much the estimate may differ from the unknown true population value. It itself is an estimate derived from the results of the survey. The smaller the standard error the more likely the estimate is close to the true value. If the sample size is large (greater then 30), the standard error can be used to derive confidence intervals. As a rule of thumb, the true value has a 95 percent confidence level of being within plus or minus two standard errors of the estimate.

Note that the standard error describes only one source of error in the estimates. It reflects the sampling error caused by selecting only a portion of the population to represent the entire population. Other sources of error exist that may affect the accuracy of the estimate. These include non-response bias, respondents not answering the questions correctly, and data entry errors. The non-sampling error is of unknown magnitude and can be contained only through careful survey design.

When data are summarized for a province or for Canada, estimates are added and the standard error is equal to the square root of the sum of squared standard errors of the individual estimates.

## Age/sex data and age ratios

The following options are offered when requesting age and sex data:

- Select a single or multiple continuous years
- Select among three spatial scale resolutions:
- By hunting zonefor a province [View map of hunting zones]
- Summarized for a single or all provinces
- Summarized for Canada

- Select by species

Here is a list of species common and scientific names (Species codes)

### Description of variables

#### Age ratio

Age ratio is calculated by dividing the number of immature parts by the number of adult parts (sexes are combined). The parts are obtained from hunters through the Species Composition Survey (Wing and Tail Survey) and have been aged and sexed by experts in waterfowl identification.

The codes used are: AF (adult female), AM (adult male), AU (adult - sex unknown), IF (immature female), IM (immature male), IU (immature - sex unknown), UM (male, age unknown), UF (female, age unknown), and UU (age and sex unknown). UM, UF, and UU individuals are not used in the calculations. Furthermore, sample size (AM+AF+AU+IF+IM+IU) must be equal to or greater than a minimum of 20 parts.

Please note that these ratios are unajusted for sampling design so care must be taken in their interpretation.

#### Proportion of immature individuals (Prop immature ind)

This is another way to express the age ratio, without a sample size constraint. The proportion is calculated by dividing the number of units classified as immature (IF+IM+IU) by the total number of units classified as adult and immature ((IF+IM+IU)/(AM+AF+AU+IF+IM+IU) x 100).

The codes used are as follows: AF (adult female), AM (adult male), AU (adult of undetermined gender), IF (immature female), IM (immature male), IU (immature individual of undetermined gender), UM (male, undetermined age), UF (female, undetermined age) and UU (undetermined age and gender). Individuals in categories UM, UF and UU are not included in the calculations.

#### Gender ratio (M:F ratio)

The gender ratio is obtained by dividing the number of units classified as male (AM+IM+UM) by the number of units classified as female (AF+IF+UF).

The codes used are as follows: AF (adult female), AM (adult male), AU (adult of undetermined gender), IF (immature female), IM (immature male), IU (immature individual of undetermined gender), UM (male, undetermined age), UF (female, undetermined age) and UU (undetermined age and gender). Individuals in categories AU, IU and UU are not included in the calculations. Furthermore, the total number of units (AM+AF+IF+IM+UF+UM) must be 20 or more.

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