The main purpose of the survey is to obtain detailed information about household spending as well as limited information on dwelling characteristics and household equipment.
Data release – January 30, 2013
The SHS primarily collects detailed information on household expenditures. It also collects information about the annual income of household members (from administrative data files), demographic characteristics of the household, certain dwelling characteristics (e.g., type, age and tenure) and certain information on household equipment (e.g., electronics and communications equipment). The survey is conducted annually in the 10 provinces and usually every other year in the territories.
The SHS combines a questionnaire with recall periods based on the type of expenditure (1, 3 or 12 months, last payment, four weeks) and a daily expenditure diary that the household completes for two weeks following the interview. As well, data collection is continuous throughout the year.
The survey adjusts collection methods and reference periods to accommodate respondents' ability to provide accurate information. In general, longer reference periods are used for goods and services that are more expensive or purchased infrequently or irregularly. On the contrary, shorter reference periods are used for goods and services that are of less value or purchased frequently or at regular intervals.
SHS data are used at Statistics Canada by the System of National Accounts, in particular as input to calculate the gross domestic product (GDP). The data also helps to update the proportions (weights) of the Consumer Price Index (CPI). In addition, many federal and provincial government departments and ministries use the data to develop social and economic policies and programs. Various groups use them to address issues directly or indirectly related to Canadians' spending habits.
The target population is the population of Canada's 10 provinces, excluding residents of institutions, members of the Canadian Forces living in military camps and people living on Indian reserves. In all, these exclusions make up about 2% of the population of the 10 provinces.
For operational reasons, people living in some remote areas where the rate of vacant dwellings is very high and where the collection cost would be exorbitant are excluded from collection. Also excluded, in addition to people living in institutions, are people living in other types of collective dwellings:
- people living in residences for dependent seniors; and
- people living permanently in school residences, hotels and motels, work camps, etc.; and
- members of religious and other communal colonies.
Collection exclusions make up less than 0.5% of the target population. However, these people are included in the population estimates to which the SHS estimates are adjusted (see the section on estimation).
Since 2010, the SHS combines the use of a questionnaire and an expenditure diary. The questionnaire is used for the most part to collect regular and less frequent expenditures during a computer assisted personal interview. The diary is used to collect frequent or less important expenditures, which are difficult to recall during a retrospective interview.
In order to introduce this new collection model, each of the many expenditure items to be collected by the SHS was assigned a collection mode in advance, which was either the questionnaire or the diary. For the questionnaire items, a reference period of one, three or twelve months, last payment, or four weeks, was also selected. Those choices were largely based on the results of qualitative tests; on the international expertise in that type of collection model; and on the studies conducted to gauge the potential increase in the variances of estimates due to shortening of reference periods. These studies were based on the data from the Consumer Expenditure Survey conducted by the U.S. Bureau of Labor Statistics.
The content of the questionnaire was determined in consultation with the primary internal and external users of the survey data. The original version of the questionnaire and of the diary were also tested during focus groups and in a pilot survey conducted in 2008.
This is a sample survey with a cross-sectional design.
The sample of the 2011 Survey of Household Spending consists of 17,873 households.
A stratified, multi-stage sampling plan was used to select the sample. It is generally a two-stage plan, the first stage being a sample of geographic areas (referred to as clusters). Then a list of all the dwellings in the selected clusters is prepared, and a sample of dwellings is selected. The selected dwellings that are inhabited by members of the target population constitute the survey's sample of households. The SHS uses a number of components of the Labour Force Survey's (LFS) sample design to minimize operating costs, though the dwellings selected are different.
The national sample is first divided among the provinces on the basis of the historical quality of SHS data and, to a lesser extent, the size of each province's population. The goal is to obtain estimates of similar quality at the provincial level. The sample sizes for the provinces are shown in Text table 1 in Section 3 of the SHS User Guide. The sample is then divided among the strata defined by grouping clusters with similar characteristics based on a number of socio-demographic variables. Some strata were defined to target specific subpopulations, such as the high-income household strata. To improve the quality of the estimates, the high-income household strata are allocated a larger share of the sample than the other strata, where an allocation proportional to stratum size is used.
Since data are collected monthly, the sample is divided into 12 subsamples of similar size. During that process, the SHS sample is coordinated with the samples of the LFS and, to a lesser extent, the Canadian Community Health Survey (CCHS), which use the same sampling frame and conduct personal interviews for part of their sample. Coordination means that, wherever possible, if a cluster is selected for more than one survey, collection for the surveys will take place in the same month. This will enable the interviewer to become familiar with the neighbourhood, collect the data and carry out the necessary follow-up for more than one survey at a time.
Data collection for this reference period: 2011-01-01 – 2011-12-31
Responding to this survey is voluntary.
Data are collected directly from survey respondents.
For the most part, the data are obtained directly from the respondent by combining two collection modes: a personal interview conducted by an interviewer using a questionnaire on a laptop, and a diary in which the household is required to report its daily expenditures over a two-week period. The data were collected on a continuous basis from January to December of the survey year from a sample of households spread over 12 monthly collection cycles.
First, households in the sample are asked to complete a questionnaire that, for the most part, collects regular expenditures (such as rent and electricity) and less frequent expenditures (such as furniture and dwelling repairs) for a reference period that varies in length depending on the type of expenditure. For regular expenditures, the last-payment method is usually used. It involves collecting the amount of the last payment and the period it covered. For the other types of expenditures collected in the interview, reference periods of one month, three months or twelve months are generally used. The periods are defined in terms of months preceding the month of the interview. For example, for a household in the June sample, "the past three months" means the period from March 1 to May 31. The demographic characteristics, dwelling characteristics and household equipment, which are also collected in the interview, relate to the household's situation at the time of the interview. In addition, respondents are asked to provide the income for the calendar year previous to the survey year for all household members aged 16 and over (at the time of the interview). However, respondents who give Statistics Canada permission to access their income tax returns are not required to answer the questions about personal income.
Following the interview, respondents are asked to record the expenditures of all household members in a daily expenditure diary for a period of two weeks starting the day after the interview. Households are required to include all their spending, except a few types of expenditures, such as rent, regular utilities payments and real estate and vehicle purchases. Households have the option of providing receipts to reduce the amount of information recorded in the diary. However, they are asked to write out additional information on the receipt if the description is incomplete.
Telephone follow-up is carried out a few days after the interview to find out if the respondent has any questions about the diary and to reiterate important information about how to complete it. At the end of the two-week period, the interviewer returns to the respondent's residence to pick up the diary and ask a few additional questions to help the respondent report expenditures that he or she might have forgotten.
The diaries and all receipts supplied by respondents are scanned and captured at Statistics Canada's Head Office. An expenditure classification code is assigned to each item from a list of more than 600 different codes.
The computerized questionnaire contains many features designed to maximize the quality of the data collected. Many edits are built into the questionnaire to compare the reported data with unusual values and detect logical inconsistencies. When an edit fails, the interviewer is prompted to correct the information (with the respondent's help, if necessary). Once the data are transmitted to Head Office, a comprehensive series of processing steps is undertaken for the purpose of detailed verification of each questionnaire. Invalid responses are corrected or flagged for imputation.
A number of edits are also carried out on the diary data when the diaries are received at Head Office and throughout the capture and coding steps. For example, checks are carried out to ensure that the start and end dates of the reference period of the diary are indicated, that the reported expenditures were made during the specified reference period, and that there are no items that appear in both the data recorded in the diary and the receipts provided by the respondent. After validation, capture and coding, quality control procedures are applied. A sample of diaries is selected and completely rechecked to ensure that the diaries were captured and coded as specified in the procedures.
Then a series of detailed edits are performed on all diaries. Invalid responses are corrected or flagged for imputation. The final step is to assess whether the information reported in the diaries is of sufficient quality using parameters which differ according to the household characteristics. The reported expenditures and number of items are compared with minimum thresholds estimated for each geographic area (Atlantic Provinces, Quebec, Ontario, Prairie Provinces and British Columbia), each household income class and each household size. Diaries that satisfy the conditions are deemed usable. The other diaries are examined. They will be deemed usable if there is a note explaining their low expenditures or their small number of reported items. Diaries that do not meet the usability criteria are treated the same as non-response diaries; they are excluded from the estimates.
To solve problems of missing or invalid information in interview questions, donor imputation by the nearest neighbour method is generally used. Data from another respondent with similar characteristics (the donor) are used to impute. The imputation is done on one group of variables at a time, with the groups formed on the basis of the relationships among the variables. The characteristics used to identify the donor are selected such that they are correlated with the variables to be imputed. Household income, dwelling type and number of adults and children are commonly used characteristics. For operational reasons, the income information from personal income tax returns is not available in time for imputation of the survey data. Consequently, the household income used for imputation is taken from an additional question on total household income that is asked during the interview exclusively for the purpose of data imputation.
Donor imputation is also used when information is missing from the daily expenditure diary. A respondent may have reported a particular expenditure item without its cost or given the total amount spent (on groceries, for example) without listing the individual items. Imputation is also used to enhance the level of detail in coding the items reported. For example, the information provided by the respondent may simply indicate that a bakery product was purchased, but a more detailed code is required to meet the survey's needs. In this case, donor imputation is used to impute the type of bakery product (bread, crackers, cookies, cakes and other pastries, etc.). Diary imputation is carried out at the reported item level, and the characteristics most often used to identify the donor are cost, available partial code, household income and household size. Imputation is done by province and quarter to control for provincial differences and seasonality of expenditures.
Expenditure imputation is performed primarily with Statistics Canada's Canadian Census Edit and Imputation System (CANCEIS).
For personal income, people who give their consent are matched to the tax data file. Missing or invalid tax data are generally donor imputed.
The estimation of population characteristics from a sample survey is based on the premise that each sampled household represents a certain number of other households in addition to itself. This number is referred to as the survey weight, and the weighting process involves computing the weight assigned to each household. There are a number of steps in that process.
First, each household is given an initial weight equal to the inverse of its selection probability. This weight is then adjusted to compensate for non-respondent households. Since a number of households answer the questionnaire but refuse to complete the diary, different weights are computed for the interview questionnaire and the diary.
The interview weights are then adjusted so that selected survey estimates agree with aggregates or estimates from independent auxiliary sources. One source is the number of people per age group and the number of households per size from population estimates produced by Demography Division from the Census 2006 data. Some of these population estimates are used on a quarterly basis to ensure that each sub-annual period is properly represented in the survey estimates. Another source is the Statement of Remuneration Paid (T4) data from the Canada Revenue Agency. This information is used to check that the survey's weighted income distribution (based on wages and salaries) is the same as that of the Canadian population.
The diary weights are adjusted to population estimates in the same way as the interview weights and to estimates of the number of households per income class by province from the interview. The adjustment to the interview estimates ensures that the weighted income distribution of diary-respondent households is consistent with the weighted income distribution of interview-respondent households.
All interview and diary expenditure variables are annualized: they are multiplied by an appropriate factor based on the reference period.
When all processing and estimation steps are complete, the data are compared with other data sources such as the Census, administrative sources and other Statistics Canada surveys. The estimates are also compared with the previous year's estimates.
Statistics Canada is prohibited by law from releasing any information it collects which could identify any person, business, or organization, unless consent has been given by the respondent or as permitted by the Statistics Act. Various confidentiality rules are applied to all data that are released or published to prevent the publication or disclosure of any information deemed confidential. If necessary, data are suppressed to prevent direct or residual disclosure of identifiable data.
Suppression rules are applied to the various tables of SHS estimates to ensure respondent confidentiality and data quality.
Approval by Statistics Canada's Microdata Release Committee is required before a microdata file may be released to the public. The committee ensures that Statistics Canada's policy requirements regarding confidentiality are met.
The method of adjusting for incomplete diaries has been refined with the 2011 SHS. As well, the age of household members is now defined to be at the time of the interview rather than as of December 31st of the survey year.
To ensure comparability of the data, the 2010 data have also been revised by incorporating these changes. The revised 2010 estimate of average household spending on all types of goods and services has increased by 1.3% when compared with the previously published 2010 estimate (April 2012).
A new methodology which combines a questionnaire and a diary to collect the household expenditures was introduced for the 2010 survey. The reference periods have been reduced for many expenditure items and collection is continuous throughout the year. Although the expenditure data collected since 2010 are similar to those of previous years, the changes to data collection, processing and estimation methods have created a break in the data series. As a result, caution should be used in comparing SHS data since 2010 with previous years, unless otherwise noted.
From time to time, revisions to past estimates may be necessary for enhancements related to new data sources, estimation methods and expenditure classifications.
The SHS estimates are subject to both sampling and non-sampling errors. Non-sampling errors can occur at any point in the collection and processing of the survey data. They take the form of coverage errors, non-response errors, response errors, capture errors, coding errors and other types of processing errors.
The interview response rate for the 2011 SHS was 66%. Among interview respondents, the diary response rate was 65%. As a result, the final diary response rate for the 2011 SHS was 43%.
While the weights of respondent households are adjusted to compensate for non-respondent households, partial non-response, such as failure to answer some questions, is handled through imputation. Various indicators associated with imputation of the interview and diary data are presented in the SHS User Guide.
The standard error is a common measure of sampling error. It is the degree of variation in the estimates due to the selection of one particular sample rather than another. The standard errors for the SHS are estimated using the bootstrap method. The coefficient of variation (CV) is the standard error expressed as a percentage of the estimate. SHS CVs are available for the national and provincial estimates as well as for the estimates by household type, age of reference person, income quintile, household tenure and size of area of residence.