3. Survey design

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• 3.1 Target population and coverage
• 3.2 Sampling design
• 3.3 Sample size and response rate

3.1 Target population and coverage

The target population of the 2012 Aboriginal Peoples Survey (APS) was composed of the Aboriginal identity population of Canada, 6 years of age and over as of February 1, 2012, living in private dwellings excluding people living on Indian reserves and settlements and in certain First Nations communities in Yukon and the Northwest Territories (NWT). These exclusions were made to avoid overlap with the First Nations Regional Early Childhood, Education and Employment Survey to be conducted in the fall of 2013 by the First Nations Information Governance Centre (see section 2.2). The census subdivisions (CSD) covered in Yukon and the NWT are listed in Table 2.

Table 2
List of census subdivisions in Yukon and NWT
Table summary
This table displays the results of list of census subdivisions in yukon and nwt. The information is grouped by territory (appearing as row headers), csd no., name of csd, csd type, 6001004, faro, t, 6001009, whitehorse, cy, 6001029, dawson, 6001044, mt. lorne, ham, 6001045, yukon, unorganized, no, 6001046, swift river, sé, 6001049, destruction bay, 6001050, stewart crossing, 6001052, keno hill, 6001055, ibex valley, 6001058, marsh lake, 6001059 and macpherson-grizzly valley, calculated using 6001060, whitehorse, unorganized, no, 6101017, inuvik, t, 6101025, aklavik, ham, 6101036, tuktoyaktuk, 6101041, sachs harbour, 6101063, region 1, unorganized, 6101095, ulukhaktok, 6102007, norman wells, 6102063, region 2, unorganized, 6103097, region 3, unorganized, 6104097, region 4, unorganized, 6105003, enterprise, set, 6105016, hay river, 6105026, reliance, 6105097, region 5, unorganized, 6106023, yellowknife, cy, 6106097 and region 6, unorganized units of measure (appearing as column headers).

Territory	CSD No.	Name of CSD	CSD type
Yukon	6001003	Watson Lake	T
	6001004	Faro	T
	6001009	Whitehorse	CY
	6001029	Dawson	T
	6001044	Mt. Lorne	HAM
	6001045	Yukon, Unorganized	NO
	6001046	Swift River	SÉ
	6001049	Destruction Bay	SÉ
	6001050	Stewart Crossing	SÉ
	6001052	Keno Hill	SÉ
	6001055	Ibex Valley	HAM
	6001058	Marsh Lake	NO
	6001059	Macpherson-Grizzly Valley	NO
	6001060	Whitehorse, Unorganized	NO
NWT	6101014	Paulatuk	HAM
	6101017	Inuvik	T
	6101025	Aklavik	HAM
	6101036	Tuktoyaktuk	HAM
	6101041	Sachs Harbour	HAM
	6101063	Region 1, Unorganized	NO
	6101095	Ulukhaktok	HAM
	6102007	Norman Wells	T
	6102063	Region 2, Unorganized	NO
	6103097	Region 3, Unorganized	NO
	6104097	Region 4, Unorganized	NO
	6105003	Enterprise	SET
	6105016	Hay River	T
	6105026	Reliance	SET
	6105097	Region 5, Unorganized	NO
	6106023	Yellowknife	CY
	6106097	Region 6, Unorganized	NO

The CSD types can be found in Table 5 of the Census Dictionary. The “Aboriginal identity population” is defined in section 3.1.1, below.

3.1.1 Identifying the Aboriginal population

The APS is a survey that selects its sample from respondents who reported either Aboriginal identity or Aboriginal ancestry to the 2011 National Household Survey (NHS) questionnaire. Although the NHS replaced the 2006 Census long form, the APS is still considered a postcensal survey, given the link between the NHS and the Census. More precisely, the APS sample was selected from respondents who gave specific answers to four screening questions on the NHS questionnaire, which had two main versions, the N1 form and the N2 form.

The N1 form was completed by self-enumeration and was administered to approximately one in three households in most parts of Canada (N1 regions). Other than the basic census demographic questions (name, sex, date of birth, legal marital status, common-law status, relationship to person 1, various language questions and the consent question to release the data in 92 years), the NHS N1 form included questions on labour market activity, income, education, activity limitations, citizenship, housing, ethnic origin, and so on.

The N2 form, identical in content to the N1 form, except for some adapted examples and excluded questions^Note1, was administered by personal interview to all households in remote areas, Inuit communities and Indian reserves and settlements (N2 regions).

The four screening questions used to identify the Aboriginal population were ethnic origin (question 17), Aboriginal self-reporting (question 18), Status Indian (Registered or Treaty Indian, question 20), and First Nation / Indian band membership (question 21).

The reporting of an Aboriginal origin in question 17 defines the Aboriginal ancestry population (or ancestry population).

The Aboriginal identity population of the NHS is derived from three questions: NHS questions 18, 20 and 21. The concept of Aboriginal identity refers to those persons who either (a) self-reported as at least one Aboriginal group, namely, First Nations (North American Indian), Métis or Inuit; and/or (b) reported being a Status Indian (Registered Indian or Treaty Indian, as defined by the Indian Act of Canada); and/or (c) reported being a member of a First Nation or Indian band.

Within the context of the APS, individuals with an Aboriginal ancestry who did not have an Aboriginal identity in the NHS are defined as the Aboriginal ancestry-only population (or ancestry-only population). For the purposes of APS sampling, the Aboriginal population includes both the identity population and the ancestry-only population. Although, in contrast to the 2006 APS, the ancestry-only population was not part of the 2012 APS target population, it was still sampled in the NHS because it was noted that in 2006, slightly less than one-third of the 2006 Census ancestry-only population had reported Aboriginal identity in the 2006 APS.

The Aboriginal identity concept in the APS is the same as that in the NHS, but is defined based on a slightly different set of questions (see Table 1 in section 2.2).

National Households Survey – N1 - question 17

17 What were the ethnic or cultural origins of this person's ancestors?

2011 National Household Survey – N1 - question 18

18 Is this person an Aboriginal person, that is, First Nations (North American Indian), Métis or Inuk (Inuit)?

2011 National Household Survey – N1 - question 20

20 Is this person a Status Indian (Registered or Treaty Indian as defined by the Indian Act of Canada)?

2011 National Household Survey – N1 - question 21

21 Is this person a member of a First Nation/Indian band?

3.1.2 Survey reference date

February 1, 2012 was used as the APS reference date. This date corresponds approximately to the beginning of data collection for the survey. Age is established based on this reference date and determines the questionnaire flow to be used.

3.1.3 National Household Survey frame

The APS sample was selected from the unedited, non-imputed database of the National Household Survey (NHS), which is the NHS database referred to as the Response DataBase or RDB. Before selecting the sample, survey methodologists developed an editing and imputation strategy to deal with missing values in any of the four NHS screening questions (or “filter questions”) or in the variables used during stratification (including age and certain education variables), as well as for individuals with certain characteristics which appeared to be inconsistent with being Aboriginal.

The first step in selecting the sample was to include on the survey frame all individuals reporting Aboriginal identity or ancestry who were aged 6 and older as of February 1, 2012.

In the second step, all individuals who were part of the same households as the units in the initial frame were added to the frame. These additional persons were retained on the frame only if their responses to screening questions were missing but the characteristics of the people in the household who had answered the screening questions indicated that they would have had a good chance of having Aboriginal identity and/or ancestry. Hence, an individual with missing screening questions on identity would normally have been imputed as having Aboriginal identity if at least 50% of the members of the same household who completed the identity screening questions had Aboriginal identity. Similarly, an individual with non-response to the ancestry screening question would normally have been imputed as having Aboriginal ancestry if at least 50% of the members of the same household who completed the screening question on ancestry had Aboriginal ancestry.

It was clearly important to stratify the 2012 APS sample by the education groups described in section 2 (current attendees, grades 1 to 6; current attendees, grades 7 to 12; high school completers or leavers). Estimates were targeted for each of these four groups. Because a person’s education status may have changed between the time of the 2011 NHS and February 1, 2012, a deterministic imputation model was developed to determine the most likely education group for each respondent as of February 1, 2012.

Once the processing was complete, individuals under 6 years of age as of February 1, 2012, those living on reserves or in certain specific communities in Yukon and the Northwest Territories and individuals who became non-Aboriginal following processing were excluded from the survey frame.

3.2 Sampling design

3.2.1 Domains of estimation

An effective stratification uses domains of estimation. Domains of estimation are groups of units for which estimates are targeted. In the case of the APS, stratification-specific domains of estimation were used. These domains of estimation corresponded to geographical regions for which estimates with an “acceptable” level of precision for a particular Aboriginal group (i.e. First Nations, Métis or Inuit) and particular education group were targeted.

An example of a domain of estimation would be Métis in Alberta attending elementary school. During stratification, the Métis Aboriginal group was comprised of individuals reporting Métis identity alone to NHS question 18 or, for individuals without Aboriginal identity (Aboriginal ancestry-only population), Métis ancestry alone to question 17 (with or without non-Aboriginal ancestry). In reality, Aboriginal ancestry-only individuals were not part of the survey’s target population but were sampled because they had a relatively important chance of reporting identity on the survey as described in section 3.1.1. This is why the term “stratification-specific domains of estimation” is used rather than the term “survey-specific domains of estimation”.

More precisely, the stratification-specific domains of estimation were created by cross-tabulating the following variables:

• Geography
  • Inuit regions
  • Outside Inuit regions
    • province/territory
    • Atlantic provinces grouped
• Education group
  • Current attendees, elementary school (grades 1 to 6)
  • Current attendees, high school (grades 7 to 12)
  • Completers: high school diploma or equivalent
  • Leavers: no high school diploma or equivalent and not currently attending elementary or high school
• Aboriginal group
  • Inuit in Inuit regions
  • Inuit outside Inuit regions (rest of Canada)
  • Aboriginal groups combined for Atlantic Canada, Quebec (outside Nunavik), Yukon and Northwest Territories (outside Inuvialuit)
  • For Ontario, Manitoba, Saskatchewan, Alberta and British Columbia
    • Status First Nations people living off-reserve
    • Non-Status First Nations people living off-reserve
    • Métis

Here is how the Aboriginal groups were defined during stratification based on responses to the NHS:

• Status First Nations people living off-reserve – persons answering First Nations alone to NHS question 18 and answering YES to NHS question 20
• Non-Status First Nations people living off-reserve  – persons answering First Nations alone to question 18 and answering NO to question 20 or persons without Aboriginal identity but responding First Nations alone to question 17 (with or without non-Aboriginal ancestry)
• Métis only – persons answering Métis only to question 18 or persons without Aboriginal identity but answering Métis alone to question 17 (with or without non-Aboriginal ancestry)
• Inuit only – persons answering Inuit only to question 18 or persons without Aboriginal identity but answering Inuit alone to question 17 (with or without non-Aboriginal ancestry)
• Multiple Aboriginal group – persons reporting more than one identity to question 18 or persons without Aboriginal identity but reporting more than one Aboriginal ancestry to question 17 (with or without non-Aboriginal ancestry)
• Status Indian or member of a First Nation / Indian band only – persons answering YES to question 20 or to question 21 but NO to question 18.

To ensure the reliability of estimates, some education groups and/or Aboriginal groups had to be combined in certain regions. Education groups were combined to reduce the number from four to two by grouping those attending elementary school with those attending high school, and completers with leavers. In Atlantic Canada outside Nunatsiavut, in Quebec outside Nunavik, in Yukon and in the NWT, the number of Métis is generally too small to be able to produce separate estimates for First Nations people and Métis by education group. For this reason, all Aboriginal groups were combined during stratification.

Note that although estimates were targeted for Inuit outside Inuit regions nationally, domains of estimation were "artificially" created for Inuit in the group of provinces from Ontario to British Columbia combined (for the other provinces and territories outside Inuit regions, all Aboriginal groups were combined). Given the small group that Inuit represent between Ontario and British Columbia, relatively imprecise estimates were targeted for two education groups only. The estimates were expected to be more precise when Inuit from other provinces/territories for Inuit outside Inuit regions nationally.

In total, 88 target domains of estimation and 92 supplementary domains of estimation were created, for a total of 180 domains of estimation. Supplementary domains of estimation included domains where there was no plan to produce estimates for the APS but where a particular group should still be represented in the sample. Examples of supplementary domains of estimation included the non-Inuit population living in Inuit regions and the population aged 45 years and older.

For each target domain, the goal was to estimate a characteristic present for at least 10% of individuals in the education groups associated with children and youth (currently attending grades 1 to 6 and currently attending grades 7 to 12) and for at least 7.5% of individuals in the education groups associated with adults (completers and leavers), with a given coefficient of variation (CV). The coefficient of variation is a measure of the precision of the estimate, which is described in section 7.2 (Sampling errors and bootstrap method). The minimum proportion targeted is referred to as “min-p”. The ability to achieve the targeted CVs for a given min-p value depended on such factors as the size of the population, the number of respondents available from the NHS, the expected response rate, the expected number of false positives (persons reporting Aboriginal identity or ancestry in the NHS without Aboriginal identity in the APS, a very specific type of respondents outside the target population), the sample loss associated with the constraint of selecting a maximum of three persons per household, and the loss associated with reducing overlap with other surveys. Depending on the domain sizes, CV values were set to 20%, 22.5%, 25% or 33%.

The following table gives the targeted CVs and min-p for each target domain of estimation.

For example, in Nunatsiavut, estimates targeted for Inuit in only two education groups: current attendees in grades 1 to 12 and completers and leavers combined. The intention was to estimate, with a CV of 20%, a minimum proportion of 10% in the first group and 7.5% in the second group. In Ontario, estimates were targeted for Status and Non-Status First Nations people separately, as well as for Métis, across the four education groups. CVs of 25% were targeted for Status and Non-Status First Nations people and CVs of 22.5% are targeted for Métis, within each education group.

Clearly, any combination of domains will give smaller CVs. Because separate estimates were targeted for Status and Non-Status First Nations people for each province between Ontario and British Columbia, CVs of 25% were set for these two groups, which should produce CVs smaller than 20% for First Nations with or without Status. CVs of 22.5% were targeted for Métis in each province between Ontario and British Columbia.

3.2.2 Stratification

Stratification will produce more precise estimates if units are homogeneous within strata and heterogeneous between strata. In addition, the estimation weights associated with survey respondents should ideally be as close as possible within strata.

The NHS design is a two-phase design in regions where the N1 form was administered (most parts of Canada, see section 3.1.1). In these regions, a systematic sample of approximately one in three households was drawn in the first phase. On July 14, 2011, those who had already responded formed the group known as the “initial respondents”. Non-respondents as of that date formed the “initial non-respondents” group. A subsample of about one in three households of these initial non-respondents (for a combined sample fraction of about one in nine) was selected for non-response follow-up (NRFU). About 40% of these individuals responded during NRFU. As a result, weights associated with NHS respondents (or more simply “NHS weights”) in N1 regions vary widely. In contrast, in regions where the N2 questionnaire was used (the N2 was administered to all households in these regions with no NRFU subsample), only non-response (and not sampling) affected the NHS weights. Thus, even with a response rate of 50% in a particular N2 region, the NHS weight would be only 2. A more detailed description of the NHS sampling design is found in Chapter 3 of the National Household Survey User Guide.

One of the assumptions used in the APS sample allocation method was that the NHS weights would vary as little as possible within an APS stratum. To this end, only part of the APS stratification came from the NHS stratification. Since the entire NHS stratification could not be used, it was necessary to select the stratification variables that caused the greatest variation possible in weights between the strata.

As previously mentioned, the type of region  (N1 or N2) associated with the type of NHS form and the collection method created a significant difference in NHS weights. An optimum allocation between N1 and N2 regions would have been to select proportionately more individuals in the APS from N1 regions than from N2 regions in order to balance the weights combining the NHS and APS sampling.

Another factor causing differences in the NHS weights in the N1 regions was whether or not the respondent was part of the non-response follow-up (NRFU) sample. The weights of NRFU respondents were on average 7.5 times higher than those of initial respondents. One possible way to have offset this effect would have been to select proportionately 7.5 times more individuals in the NRFU respondent strata than in the initial respondent strata. However, this type of approach could have had numerous disadvantages (such as not being able to select enough NRFU respondents and the fact that the probabilities of response to the APS are definitely less among NRFU respondents than among initial respondents). Certain compromises had to be made during sample allocation.

Another factor, unrelated to the variability of NHS weights, but one that was very important to consider as a stratification factor was the type of Aboriginal identification (or more simply “Aboriginal type”) of the respondent selected from the NHS. This factor refers to the fact that the NHS respondent indicated either Aboriginal identity (ID) or Aboriginal ancestry-only (AO) in the NHS. These two groups have very different characteristics. Moreover, allocation must reflect the probability of each unit being part of the target population (having Aboriginal identity on the APS). Nationally, based on the 2006 APS data, individuals having identity on the NHS have a probability of about 88% of having identity on the APS, while individuals with ancestry-only on the NHS have a probability of about 32% of having identity on the APS.

Combining the factors type of region (N1 or N2), type of NHS respondent (initial respondent or NRFU respondent) and Aboriginal type (AO or ID) gave a maximum of six strata per domain of estimation:

• N1, initial respondent, AO
• N1, initial respondent, ID
• N1, NRFU respondent, AO
• N1, NRFU respondent, ID
• N2, AO
• N2, ID

For certain domains such as Status First Nations, there were only three possible strata because included individuals had Aboriginal identity by definition. Some strata may also have been empty, especially in the supplementary domains. For example, for a specific Inuit region, it was possible that no one classified as Aboriginal ancestry-only had Aboriginal ancestry other than Inuit.

3.2.3 Sampling design and sample allocation

The 2011 APS selected its sample from 2011 NHS respondents. Section 3.2.2 described how the NHS used a two-phase sampling design in the N1 regions and a single-phase sampling design in the N2 regions. Thus, the APS sampling design can be considered a three-phase design in the N1 regions and a two-phase design in the N2 regions.

Once the frame had been constructed, it was stratified according to domain of estimation and then substratified by type of region (N1 vs. N2), type of NHS respondent (initial respondent vs. NRFU respondent) and Aboriginal type (ID vs. AO). A systematic random sample was then selected within each stratum, the frame having been pre-sorted by household and person number. The purpose of this was to ensure proper distribution of the sample geographically within the strata as well as across as many households as possible. This procedure was, however, limited by the fact that members of the same household  can be in different strata.

A method for optimal allocation between the substrata of a particular domain was used by taking into account the different types of sample size loss as described in section 3.2.4 as well as the probability of each unit belonging to the target population in a given stratum. This allocation depended in part on the NHS weights. It should be noted that at the time of the allocation, these weights had not yet been calculated. Preliminary weights were therefore derived solely for the allocation. The definitive weights derived by the methodology team working on the NHS estimates were used during weighting (see section 6). For a reference on this topic, see Verret (2013).^Note2

Allocation was done in the survey’s target domains first. For the non-targeted or supplementary domains (for example, non-Inuit in Inuit regions or persons 45 and over among school completers and leavers), the sample size in a given stratum was calculated using a sampling fraction equal to or less than the sampling fraction of the corresponding stratum in the corresponding target domain. These supplementary domains had to be retained in order to cover the entire target population but did not require a specific sample size since no estimates were to be derived for them. For non-targeted Aboriginal groups, such as non-Inuit in Inuit regions, the same sampling fraction as for Inuit was used. For persons 45 and over, half of the sampling fraction of persons under 45 was used.

Although the plan was to select the 2012 APS sample in a single wave, after a few weeks of collection, it was decided to select a top-up sample (called the wave 2 sample). There were three reasons for this decision:

• Since the RDB (APS sampling frame) had not been fully edited at the time of APS sample selection, a number of individuals appeared as Status Indians or as members of First Nations / Indian bands only (see section 3.2.1). The initial APS sample contained 1,254 of these cases. These units will be referred as “false Aboriginal individuals” later in this guide;
• The response rate among school leavers was lower than for the other groups and also lower than expected;
• The proportion of the sample in Quebec belonging to the target population (rate of Aboriginal identity on the survey) was lower than expected for both those who had the identity on the NHS and those who had Aboriginal ancestry-only on the NHS.

To calculate the size of the top-up sample, the “false Aboriginal individuals” were first removed from the survey frame. The response rates among school leavers were adjusted downward and the identity rates on the survey were reviewed for Quebec based on the results observed at the start of collection. The same allocation method was then used to determine new sample sizes. The sample size obtained using this method represents the size that would have been used if the “false Aboriginal individuals” had never existed on the frame and if it had been possible to more precisely estimate the response rates of school leavers and identity rates in Quebec. The difference between this sample size and the size of the initial sample constitutes the size of the top-up sample. No additional units were selected in the supplementary domains. After removing the “false Aboriginal individuals”, the initial sample contained 49,287 units and the top-up sample 1,737 units, for a total of 51,024 units.

3.2.4 Sample size adjustment

a) Probability of belonging to the target population

The 2006 APS found that 88% of individuals with Aboriginal identity in the 2006 Census  reported Aboriginal identity in the 2006 APS and 32% of those with ancestry-only in the 2006 Census  reported identity in the 2006 APS.  As a result of changes in the survey methodology, questionnaire and in social environment, these probabilities of belonging to the target population were expected to be lower in 2012 than in 2006. Accordingly, the probabilities of belonging to the specified 2012 target population were adjusted downward by multiplying 2006 figures by 75% in the NHS Aboriginal ancestry-only strata and by 95% in the NHS identity strata.

b) Response rates

Response rates from the 2006 APS were used to allocate the sample for the 2012 APS. As a preventive measure, these rates were reduced by multiplying them by an adjustment factor of 90%. Note that increasing the sample size based on an expected response rate is a protective measure to reduce sampling error but does nothing to reduce non-response bias, a particular type of non-sampling error (see section 7.3). Clearly, it is preferable to obtain a higher response rate on a smaller sample size than a lower response rate on a larger sample size.

c) Transition between educational groups

Estimates were targeted for four education groups (or sometimes two) per region and Aboriginal group. However, the classification of individuals among these groups was done using education and age variables, which can sometimes be inaccurately reported  or missing on the NHS. In many cases, and for children in particular, educational attainment could only be approximated using NHS data (in fact, only date of birth was used to determine the education group of children under 15 years of age). As well, changes over time meant that NHS data could not allow for a prediction of the exact educational group of APS respondents as of February 1, 2012, the survey’s reference date.

Loss factors related to transitions between groups were estimated for the 2012 APS, always using 2006 data. For 2006 APS respondents, education groups were derived based on the 2006 Census RDB data and the categorizations were compared to the education groups obtained during the 2006 APS. The 2006 APS results had shown slightly more individuals than expected  attending elementary school (2.5% more), fewer individuals than expected attending high school (8.5% less), slightly fewer school completers than expected (5.8% less), and more school leavers than expected (15% more). Size adjustments factors were calculated by region, Aboriginal group and education group. These factors were multiplied by 1.05 as a precaution measure. If a factor was still smaller than 1, the factor was simply raised to 1 so as not to reduce sample sizes. For example, even though more school leavers were expected on the APS than on the NHS,  the size of the leavers group was not reduced as a precaution. These factors were included in the allocation process in order to increase (or not) the sample size accordingly.

d) Households with more than three individuals selected

Because the sample unit was the individual and not the household, the sample may have included several individuals from a single household. To limit response burden, one of the constraints imposed during collection was to select no more than three individuals per household. As a way to estimate this loss, a preliminary sample was selected and the number of persons who would have been removed from the sample because of this constraint was calculated. The relative loss obtained was multiplied by 1.1 for each combination of domains and strata and was incorporated in the sample size adjustment factor.

e) Overlap with other surveys

The APS collection period overlapped with that of several other Statistics Canada surveys. It is generally understood that an individual contacted for one survey is less likely to agree to participate in that survey if he or she has just been interviewed for another survey. To compensate for this potential loss, the total sample size of the 2012 APS was increased uniformly by about 5%. Several of the overlapping surveys also covered the territories where the Aboriginal population represents a high portion of the total population. Therefore, there was a higher possibility of overlap between the different surveys in the territories. Special attention was given to this matter in order to reduce overlap as much as possible and, implicitly, to reduce the potential burden on respondents. Overlap in the territories was examined for the Canadian Community Health Survey (CCHS), the Labour Force Survey (LFS) and the Programme for the International Assessment of Adult Competencies (PIAAC) and steps were taken to minimize response burden where possible.

For example, overlap with the CCHS was of particular concern. Some of the APS questions on health are drawn directly from the CCHS survey, including several highly sensitive questions on mental health. No measures were taken for the CCHS interviews held before and after the APS collection, that is, before January 2012 and after June 2012. However, the identifiable overlap in households to be interviewed between January 2012 and June 2012 for the CCHS was eliminated. It should be mentioned that the area frame of the LFS (from which the CCHS sample is selected) had been matched with the Census resulting in approximately 70% of the households of the area frame being matched to the Census. Since the CCHS selects a systematic random sample of households within each community covered, households not drawn also form a systematic random sample of households. Households selected for the CCHS between January and June and which had responded to the NHS were removed from the APS survey frame. Within each community covered by the CCHS, the weights of the remaining NHS households were adjusted to represent all of the community’s households. Since these households had been removed from the APS survey frame, they therefore had no chance of being selected.

3.3 Sample size and response rate

The initial and top-up sample of the 2012 APS contained a total of 51,024 units, 376 of which were removed before being sent to collection (see section 6.2). Table 4 shows the allocation of the 50,648 units sampled by geographical domain and the corresponding response rates.

A response rate is defined as the number of eligible respondents divided by the number of eligible units in the sample. Persons living outside of Canada or in an institution at the time of the survey or under 6 years of age as of February 1, 2012 are examples of ineligible units for the APS.

Two definitions of eligible units were used for the APS. In the first definition, individuals without Aboriginal identity on the APS were deemed ineligible (in addition to the other types of ineligible units). In the second definition, these individuals were deemed eligible and were included as respondents. Indeed, these individuals agreed to participate in the survey and completed all of the questions administered to them, that is, the screening questions determining whether or not they have Aboriginal identity.

These two definitions of eligible units and respondents therefore offer two ways to measure the response rate. The first response rate of 70.4% is generally the response rate used during collection. This is a response rate relative to the sampled units falling within the APS identity population. The second response rate of 76.2% is the one used by Methodology and is more a response rate relative to all sampled units (with some exclusions, however). Of course, in both cases, non-responding units cannot always be classified as being eligible or not eligible. Given that the probability of having identity on the APS differs substantially between individuals with Aboriginal identity on the NHS and those with ancestry-only on the NHS, the response rate used during collection is highly influenced by the allocation of the sample between these two groups, which is not the case for the response rate used by Methodology. In Inuit regions, because most individuals have identity, the two response rates are quite similar, which is not the case in the other regions. The maximum difference between the two rates occured in Quebec outside Nunavik. In this region, the Aboriginal ancestry-only population forms a large part of the total Aboriginal population and, according to the 2006 APS, the probabilities of having Aboriginal identity on the survey are the lowest in the country regardless of whether the individual has Aboriginal ancestry-only (20%) or Aboriginal identity on the NHS (66%). Therefore, although the methodology response rate is the highest in Quebec, the corresponding data collection response rate is relatively low.

Table 4
Sample size and response rate by geographical domain using two definitions
Table summary
This table displays the results of sample size and response rate by geographical domain using two definitions. The information is grouped by geographical domain (appearing as row headers), total, eligible 1, eligible 2, respondents 1, respondents 2, response rate 1 and response rate 2, calculated using number of units and percentage units of measure (appearing as column headers).

Geographical domain	Total	Eligible 1	Eligible 2	Respondents 1	Respondents 2	Response rate 1	Response rate 2
	number of units					%
Nunatsiavut	777	752	759	604	611	80.30%	80.50%
Nunavik	2,084	2,000	2,021	1,543	1,564	77.20%	77.40%
Inuvialuit	1,153	1,117	1,139	791	813	70.80%	71.40%
Nunavut	2,181	2,128	2,156	1,581	1,609	74.30%	74.60%
Nunangat (total)	6,195	5,997	6,075	4,519	4,597	75.40%	75.70%
Atlantic excluding Nunatsiavut	3,352	2,640	3,336	2,025	2,721	76.70%	81.60%
Quebec excluding Nunavik	6,776	3,155	6,724	2,317	5,886	73.40%	87.50%
Ontario	8,366	6,299	8,306	4,286	6,293	68.00%	75.80%
Manitoba	5,190	4,589	5,136	3,006	3,553	65.50%	69.20%
Saskatchewan	4,946	4,412	4,860	3,124	3,572	70.80%	73.50%
Alberta	6,603	5,477	6,547	3,765	4,835	68.70%	73.90%
British Columbia	6,963	5,707	6,901	3,918	5,112	68.70%	74.10%
Yukon	786	712	764	489	541	68.70%	70.80%
Northwest Territories excluding Inuvialuit	1,471	1,365	1,440	960	1,035	70.30%	71.90%
Rest of Canada (total)	44,453	34,356	44,014	23,890	33,548	69.50%	76.20%
Canada (total)	50,648	40,353	50,089	28,409	38,145	70.40%	76.20%
Eligible 1 Sample size excluding out of scope on the APS (non Aboriginal individuals are out of cope under this definition) Eligible 2 Sample size excluding out of scope on the APS (non-Aboriginal individuals are in scope under this definition) Respondents 1 Number of respondents excluding non-Aboriginal individuals on the APS Respondents 2 Number of respondents including non-Aboriginal individuals on the APS Response rate 1 Response rate excluding non-Aboriginal individuals on the APS Response rate 2 Response rate including non-Aboriginal individuals on the APS

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Notes

1. The questions on citizenship (question 10), immigrant status received (question 11) and year of immigration (question 12) are not asked of people living on Indian reserves and settlements who were enumerated using the N2 form.
2. Verret, F. (2013). The estimation methodology of the 2011 National Household Survey.
   Paper presented at the 2013 Joint Statistical Meeting.