Canadian Health Measures Survey (CHMS)
Detailed information for November 2022 to September 2024 (Cycle 7)
Every 2 years
The Canadian Health Measures Survey (CHMS) aims to collect important health information through a household interview and direct physical measures at a mobile examination centre (MEC), sometimes referred to as a mobile clinic.
Data release - To be determined
- Questionnaire(s) and reporting guide(s)
- Data sources and methodology
- Data accuracy
The Canadian Health Measures Survey (CHMS), launched in 2007, is collecting key information relevant to the health of Canadians by means of direct physical measurements such as blood pressure, height, weight and physical fitness. In addition, the survey is collecting blood and urine samples to test for chronic and infectious diseases, nutrition and environment markers and is storing blood, urine and saliva samples at the Statistics Canada biobank for future health research projects.
Through household interviews, the CHMS is gathering information related to nutrition, smoking habits, alcohol use, medical history, current health status, sexual behaviour, lifestyle and physical activity, the environment and housing characteristics, as well as demographic and socioeconomic variables.
All of this valuable information will create national baseline data on the extent of such major health concerns as obesity, hypertension, cardiovascular disease, exposure to infectious diseases, and exposure to environmental contaminants. In addition, the survey will provide clues about illness and the extent to which many diseases may be undiagnosed among Canadians. The CHMS will enable us to determine relationships between disease risk factors and health status, and to explore emerging public health issues.
CHMS data are representative of the population whether they are healthy or not and provide a better picture of the actual health of Canadians.
The following are some of the measures that the CHMS includes:
- Anthropometry (standing height, sitting height, weight, waist circumference)
- Cardiovascular health and fitness (resting heart rate and blood pressure)
- Musculoskeletal health and fitness (DXA)
- Physical activity (accelerometry)
- Oral health
- Nutritional status (e.g., Vitamin B12, Vitamin D, ferritin)
- Diabetes (e.g., glucose, glycated hemoglobin A1c)
- Cardiovascular health (e.g., apolipoprotein A1 and B, lipid profile)
- Environmental exposure (e.g., flame retardants, polycyclic musks, metals and trace elements)
- Environmental exposure (e.g., bisphenol analogues, flame retardants, pesticides, metals and trace elements)
- Nutritional status (e.g., iodine, sodium, potassium)
Tap water measures
- Environmental exposure (e.g., fluoride, metals and trace elements)
The CHMS team works closely with the Health Canada and Public Health Agency of Canada Research Ethics Board and the Office of the Privacy Commissioner of Canada in order to address privacy issues and to implement proper laboratory procedures.
Reference period: Varies according to the question (for example: "over the last 12 months," "over the last 6 months," "during the last week")
Collection period: September - September
- Diseases and health conditions
- Environmental factors
- Lifestyle and social conditions
Data sources and methodology
The target population for CHMS consists of persons 1 to 79 years of age living in the ten provinces.
The observed population excludes: persons living in the three territories; persons living on reserves and other Aboriginal settlements in the provinces; the institutionalized population and residents of certain remote regions. Altogether these exclusions represent approximately 4% of the target population.
Two questionnaires were used for cycle 7 of the Canadian Health Measures Survey:
1) Household questionnaire:
The household questionnaire content was developed with input from stakeholders (Health Canada and the Public Health Agency of Canada) and from external experts who participated as members of various advisory committees. Much of the cycle 7 household questionnaire was the same as the cycle 6 questionnaire, with questions added or removed to reflect the content changes of cycle 7.
Prior to finalizing the questions, one-on-one qualitative test interviews were conducted to look at specific questionnaire content, particularly the content new to cycle 7. As a result of this testing, improvements were made to questionnaire wording and instructions and to the flow of questions.
2) Clinic questionnaire:
Development of the clinic questionnaire proceeded in much the same way as that of the household questionnaire. Content was determined through a comprehensive consultation process and multiple iterations of the collection application were generated. Each iteration was assessed on flow within the mobile examination center (MEC) for both the respondent and staff. Quantity and quality of data collected was also assessed.
The clinic questionnaire includes a set of self-reported health questions similar to the type of questions asked within the household questionnaire. The questions included at the MEC were related to medication use and fish and shellfish consumption. In addition, the clinic questionnaire includes introductory text/instructions and screening and administrative questions related to the physical measures tests conducted at the MEC.
This is a sample survey with a cross-sectional design.
The Canadian Health Measures Survey uses a stratified three-stage sample made up of one or two selected respondents from each dwelling selected in a sampled collection site.
The sampling unit at the first stage is a collection site. A collection site is a geographical unit limited to a radius of about 50 km in urban areas and up to 75 km for rural areas. The sampling unit at the second stage is the dwelling and at the third stage, the sampling unit is the person.
Strata are defined at every stage. At the first stage, collection sites are stratified in the 5 Canadian regions (Atlantic, Quebec, Ontario, Prairies, and British Columbia).
At the second stage, dwellings are stratified in 8 hierarchical groups defined according to the presence or not of age groups and derived using the household composition obtained from recent auxiliary information:
1) dwellings with 1 to 2 year-olds, else
2) dwellings with 3 to 5 year-olds, else
3) dwellings with 6 to 11 year-olds, else
4) dwellings with 12 to 19 year-olds, else
5) dwellings with 60 to 79 year-olds, else
6) dwellings with 20 to 39 year-olds, else
7) dwellings with 40 to 59 year-olds, else
8) other dwellings without household composition or with all ages outside the ones above.
Finally, at the third stage, the persons in the household at the time of interview are stratified in three clusters prior to selection:
1) 1 to 2 year-olds, 6 to 11 year-olds, and 60-79 year-olds.
2) 3 to 5 year-olds and 12 to 79 year-olds
3) 20 to 59 year-olds.
If all three clusters are populated, then two clusters are selected at random using PPS sampling, otherwise one or two clusters populated are automatically selected. One person is then randomly chosen from each of the selected clusters. Between one and two people are selected from each in-scope household.
SAMPLING AND SUB-SAMPLING
The Canadian Health Measures Survey consists of a full sample and several subsamples.
For the full sample, at the first stage, a sample of 16 collection sites was required. The sites are allocated by region: Atlantic (2), Quebec (4), Ontario (6), Prairies (2) and British Columbia (2). Within each region, sites are sorted according to the size of their population and whether or not they belonged to a census metropolitan area. Within the Prairies and Atlantic regions, they were first sorted by province. Sites are then randomly selected using a systematic sampling method with probability proportional to the size of each site's population.
The sample size determination and allocation for the second and third stage are done together. The target sample size for cycle 7 is 6,500 respondents for the clinic component of the survey, which works out to approximately 356 respondents per collection site. To determine the number of dwellings to sample in each collection site to reach this target, previous response rates were used from the CHMS. This data is used to calculate:
- The expected probability that a dwelling would be eligible for the CHMS (the eligibility rate)
- The expected probability that a roster of all occupants of the household would be completed (the roster rate)
- The expected probability that a selected person would respond to the household questionnaire (the questionnaire rate)
Finally, rates from the previous CHMS sites are used to calculate the expected probability that a household questionnaire respondent would also be a respondent to the clinic (the clinic rate). Since outside CMA, inside CMA urban and inside CMA urban core (downtown) collection sites each have distinct response rates, each collection site is classified into one of these three categories and the previously mentioned response rates are calculated and applied separately for each category. The distinction between urban and urban core collection sites within the CMAs is based on the dissemination blocks from the census, which are the lowest level of geography used by the census. If a collection site within a CMA has at least 80% of its dissemination blocks designated as core, it is designated as an urban core collection site. If the rate was less than 80%, it is designated as an urban collection site.
For each site, a model is used to combine the historical CHMS data and the current cycle sample design to predict actual and effective sample sizes for each age-sex group of interest for each site. The sample design features, such as the dwelling allocation across the strata and the person selection weights used to drive the PPS selection within the clusters are altered in an iterative fashion until the final sampling parameters are settled upon.
Once all of the previous response rates are calculated, a simulation of 100 independent samples of dwellings is performed for the site being sampled. The goal of each of the 100 simulated samples is to use the expected response rates to predict if each sampled dwelling results in 0, 1 or 2 people responding to the clinic. The final frame for the site is used for each simulation. The average expected number of clinic respondents for each age and sex group over the 100 independent samples is used to determine if the specified sample size and allocation are sufficient. The entire simulation of 100 independent samples is performed multiple times with varying sample sizes and allocations in order to settle on a final overall sample size and allocation strategy. The first iteration uses approximate age/sex targets to come up with starting values for the overall sample size and the stratum allocation. Subsequent iterations require manually adjusting the overall sample size and stratum allocation, based on the previous iteration, to produce final values that satisfy the clinic target counts.
The sample is allocated amongst the 7 age group strata (1-2, 3-5, 6-11, 12-19, 20-39, 40-59 and 60-79), with a small portion of the sample going to an "other" stratum. A maximum number of 35 dwellings per site is selected in this stratum, with fewer being selected for sites that had fewer dwellings in the stratum. This stratum size helped to prevent extreme dwelling sampling weights.
The allocation of the dwelling sample to each of the age group strata is done to allow for the best chance of meeting the age and sex clinic respondent targets for cycle 6 without going too far over. Where possible, the sample is allocated in a way that emphasized the strata where more sample was required to meet the targets.
Once the sample of dwellings is in the field, when the household interviewer makes contact with a sampled dwelling, the goal is to create a roster for the household. A roster is a list of all persons residing in the household and includes pertinent information such as age, sex and whether the individual works full-time for the Canadian Forces. With this information, the computer application randomly selects one or two persons to take part in the remaining part of the survey, including the questionnaire and the clinic visit.
Among the full sample respondents, several subsamples will be selected.
Data collection for this reference period: 2022-11-01 to 2024-12-31
Responding to this survey is voluntary.
Data are collected directly from survey respondents.
Collection includes a combination of a personal interview using a computer-assisted interviewing method and, for the physical measures, a visit to a mobile examination centre (MEC) specifically designed for the survey.
The CHMS will collect data in 16 sites across the country. The collection sites are located in seven provinces: Nova Scotia, New Brunswick, Quebec, Ontario, Saskatchewan, Alberta and British Columbia. Collection is scheduled so that each region is distributed within the two-year collection period, distributed between seasons and in a way that tries to minimize the movement of staff and equipment between sites. The CHMS MEC stays in each site for five to seven weeks, collecting direct measures from approximately 410 to 470 respondents per site.
First step: personal interview at the household
The first contact with respondents is a letter sent through the mail. The letter informs people living at the sampled address that an interviewer will visit their home to collect some information about the household.
At the home, the application randomly selects one or two respondents and the interviewer conducts a separate health interview with each of them. The interview takes 45 to 60 minutes per respondent. The interviewer then assists the respondent in setting an appointment for the physical measures at the CHMS MEC.
Second step: visit to the CHMS MEC
Statistics Canada uses MECs to conduct the physical measures portion of the survey. Similar MECs have been used successfully for years by the National Health and Nutrition Examination Survey (NHANES) in the United States.
The MEC consists of three trailers (side by side), linked by enclosed pedestrian walkways. One trailer serves as a reception and administration area, the second trailer contains a laboratory and physical measure rooms, while the third trailer contains additional physical measure rooms.
For each respondent, the complete visit to the MEC lasts about two hours. This is an approximate time, given that each respondent is assessed for their suitability for each measure and tested accordingly.
For children under 15 years of age, a parent or legal guardian has to be present with the child at the MEC and has to provide written consent for the child to participate in the tests.
At the end of their visit to the MEC, respondents are provided with a waterproof activity monitor. This small device is worn for a week at all times - even when swimming or bathing. It records information about normal physical activity patterns and sleep without the respondents having to do anything special.
Respondents are also provided with materials to send a second urine sample from home to a laboratory for nutritional analysis.
View the Questionnaire(s) and reporting guide(s).
Most editing of the data was performed at the time of the interview by the CAI application. It was not possible for interviewers/HMS to enter out-of-range values and flow errors were controlled through programmed skip patterns. For example, CAI ensured that questions that did not apply to the respondent were not asked. Edits requiring corrective action were incorporated in the CAI application to deal with inconsistent responses. In addition, warnings not requiring corrective action were also included to identify unusual (i.e., improbable rather than impossible) values as a means of catching potential errors and allowing correction at source.
At head-office, the data underwent a series of processing steps that resulted in some of the data being adjusted. As a final validation step, the CAI edits were re-applied to the processed data. As a result, the final data were complete and contained reserve codes for responses of "less than limit of detection", "valid skip", "don't know", "refusal" and "not stated".
Table 8.1 Reserve code of responses
Reserve Code label Reserve code
Less than limit of detection 9.5, 95, 99.5 etc.
Valid Skip 6, 96, 99.6 etc.
Don't Know 7, 97, 99.7 etc.
Refusal 8, 98, 99.8 etc.
Not Stated 9, 99, 99.9 etc.
When necessary, total household income is imputed for this survey.
In order for estimates produced from survey data to be representative of the population covered and not merely of the sample itself, users must incorporate weighting factors (survey weights) into their calculations. A survey weight is assigned to each person included on the final dataset, that is, in the sample of persons who responded to the entire survey. This weight corresponds to the number of people represented by the respondent in the population as a whole.
The survey weight is calculated as the inverse of the probability that the respondent was selected for the survey. The Canadian Health Measures Survey (CHMS) is a multi-stage sample. The probability of selection for the survey is determined by multiplying the probability of selection at each stage.
In accordance with the weighting strategy, the selection weights for collection sites are multiplied by the selection weights for dwellings (households) and adjusted for non-response. The weight of non-respondent households is redistributed to respondents within homogeneous response groups (HRGs). In order to create these HRGs, a method based on logistic regression is used: first a logistic regression model is created to estimate the response probability, and then these probabilities are used to divide the sample into groups with similar response properties. The logistic regression models are created from the limited amount of information available for all households. This includes data from the frame such as the strata, and geographic location, and paradata about the data collection such as the number of attempts to contact the household and the elapsed time between the first and last contact. An adjustment factor was then calculated within each HRG. The weight of respondent households is multiplied by this adjustment factor to produce the adjusted household weight.
Since the final sampling unit for the CHMS is the person, the adjusted household weight up to this point must be converted into a person weight. This is obtained by multiplying the adjusted household weight by the inverse of the probability of selection of the person selected in the household.
The selected person is asked to complete an interview. In some cases, interviewers do not succeed in completing it either because they cannot contact the person(s) selected, or because the person or persons selected refuse to be interviewed. Such cases are defined as non-responses at the questionnaire level, and an adjustment factor must be applied to the weights of respondent persons to compensate for this non-response. Just as for non-response at the dwelling (household) level, the adjustment is applied within classes defined by a method using response probabilities from a logistic regression model. The model is based on the characteristics available for all respondents and non-respondents, which includes all the characteristics collected when the members of the household are listed, such as the number of persons in the household, in addition to geographic information and paradata. An adjustment factor is calculated within each class. The weight of respondent persons is multiplied by this adjustment factor.
Respondents to the questionnaire are then invited to go to the CHMS Mobile Examination Center for physical measurements. In some cases, people refuse to participate or do not keep their appointment at the MEC. Such cases are defined as non-responses at the MEC level, and to compensate for this non-response, an adjustment factor must be applied to the weights of the MEC participants. Just as for non-response at the dwelling (household) and questionnaire levels, the adjustment is applied within classes defined by their probability of attending the MEC. This probability is obtained from a logistic model using the characteristics available for respondents and non-respondents. All the characteristics collected on the questionnaire during the interview (such as income class, whether or not the respondent is employed, general health status, and frequency of smoking), in addition to geographic information and paradata, were made available to create the non-response models. An adjustment factor is calculated within each class. The weights of the persons participating at the MEC were accordingly multiplied by this adjustment factor.
The next step is calibration. This procedure is applied to ensure that the sum of the final weights corresponds to the estimates of populations defined at the scale of the five Canadian geographic regions, for each of the 14 age-sex groups of interest, the seven age groups 1 to 2, 3 to 5, 6 to 11, 12 to 19, 20 to 39, 40 to 59 and 60 to 79 for each sex. The population estimates are based on the most recent census counts, as well as on counts of births, deaths, immigration and emigration since then. The calibration was carried out using the mean of the monthly estimates (covering the survey period) for each cross-tabulation of standard regional boundaries and age-sex groups.
Note that following a series of adjustments applied to the weights, it is possible that some units will have weights that stand out from the other weights to the point of being aberrant. Some respondents may actually represent an abnormally high proportion in their group and therefore strongly influence both the estimates and the variance. To avoid this situation, a respondent weight that contributes aberrantly to the age-sex group is adjusted downward using a method known as "winsorization." In this process, respondent weights that are considered to be outliers are replaced by the highest non-outlier weight for that age and sex group. All of the weights are then adjusted to redistribute the surplus weight (the part of the weight that is higher than the highest non-outlier weight). This is done by multiplying the non-outlier weights by an adjustment factor to create the winsor adjusted weights.
A second calibration (an exact repetition of the first calibration) is done on the winsorized weights to produce the final weight.
The CHMS uses a complex sampling design to select the sample and there are no simple formulas that can be used to calculate the variance of the survey estimates. Instead, a re-sampling approach known as the bootstrap method is used to approximate the sample variance. The bootstrap method involves creating subsamples of the full sample by randomly selecting « n-1 » collection sites with replacement among the « n » collection sites in each region. An adjusted weight is then calculated for each respondent in the selected subsample. This is repeated 500 times to create the bootstrap weights. To calculate the variance of a point estimate (such as the mean), the estimate for each of the 500 replicates is calculated using the bootstrap weight. The variability among the 500 estimates gives the variance estimate.
For the subsamples, additional weighting steps are done.
The fasted subsample was selected when the sample of dwellings were selected, and thus occurred prior to completion of the household questionnaire. To create the fasted subsample weights, the subsample flags that were assigned to the dwellings were attributed to the selected person(s). Before adjusting for non-response at the questionnaire level, the person weight of those selected for the fasted subsample was adjusted to incorporate the subsample sampling weight. An additional step was required to adjust for persons who were selected for the subsample but who did not fast or did not provide blood. Such cases were defined as non-respondents to the fasted subsample and to compensate for this non-response an adjustment factor was applied to the weights of the persons with a valid measure.
A separate weight was created for the activity monitor data for respondents who had at least 4 days of valid data (3 days of valid data for youths 3 to 5 years old). Respondents who did not have the required number of valid days were treated as non-respondents to the activity monitor. The weights of respondents with the required number of days were adjusted to compensate for any bias due to this non-response.
One of the unique features of the Canadian Health Measures Survey (CHMS) is that three different sets of data are collected for the same respondent: household interview data, physical measures data, and laboratory results data. Each set of data has to be processed on its own, yet they cannot be completely separated from each other because at various points during processing the three sets of data have to be used together.
The processing of the household interview data was performed in a manner similar to that of other health surveys at Statistics Canada. The data are validated first at the record level and then at the individual variable level, followed by detailed top-down editing. During data collection, processing takes place on a daily basis. The household interview responses have to be processed quickly in order for the data to be available at the mobile examination centre (MEC) in time for the respondent's visit to the MEC.
Similarly, the processing of the physical measures data begins with the data being validated first at the record level and then at the individual variable level, followed by detailed top-down editing. Also, because the laboratory tests are determined based on responses received at the MEC, the MEC data are used to generate a file containing a list of the tests for which laboratory results are expected to be received. This laboratory "control" file is used in processing the laboratory results data.
The processing of the laboratory data involves significant file manipulation due to the fact that several different file types are received from the MEC and the various reference laboratories. As with the household and the physical measures data, the laboratory data are validated at the record level and at the individual variable level, and several new variables are then derived. The laboratory data are processed as quickly as possible so that any results that have been identified as outside of a normal range at the reference laboratories and the MEC are available in a timely fashion for reporting to respondents.
Statistics Canada is prohibited by law from releasing any information it collects that 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.
Revisions and seasonal adjustment
This methodology does not apply to this survey program.
The survey aims at producing unbiased national estimates with a coefficient of variation (c.v.) of 16.5% or less for each of the 5 age groups (6-11, 12-19, 20-39, 40-59, and 60-79) by sex and for 1-2 and 3-5 year olds of both sexes combined. Examples of estimations and accuracy measures (c.v.) can be seen at the link below.
For the full sample, accuracy measures are provided for the average body mass index and for a selected non-environmental measure on blood (High-density lipoprotein cholesterol) and the fasted subsample (glucose). As well estimations and accuracy measures are provided for the accelerometer subsample (Average time spent sedentary (minutes per day)).They can be seen at the link below.
Cycle 7 response rates are not currently available as collection is currently ongoing.
In cycle 6, 9,143 dwellings were selected within the scope of the Canadian Health Measures Survey (CHMS). Of these dwellings, 6,737 agreed to provide information on the composition of the household, for a household response rate of 73.7%. From these respondent households, 9,306 persons were selected (one or two persons per household) to participate in the survey, of whom 8,286 responded to the questionnaire, for a response rate of 89.0%. Of these persons, 5,797 then reported to the CHMS mobile examination centre (MEC) for physical measurements, for a response rate of 70.0%. At the Canadian level, a combined response rate of 45.9% was observed for cycle 6 of the CHMS. It is important to note that the combined response rate is not obtained by multiplying the response rates at the person and household levels (or questionnaire level and the MEC level), since two persons were selected in some households.
Therefore a response rate is derived for each of these components (blood and urine) that were supposed to be done on the full sample respondents. The response rates for these measures use the full sample response rates up to the MEC and derive the rest in the following manner. Of the 5,797 participants who reported to the CHMS MEC for physical measurements, 5,471 participants provided blood and 5,651 provided urine. The combined response rate for blood draw was 43.7% whereas the combined response rate for urine was 44.9%.
The CHMS covers the population 1 to 79 years of age living in the ten provinces. Excluded from the survey's coverage are: persons living in the three territories; persons living on reserves and other Aboriginal settlements in the provinces; full-time members of the Canadian Forces; the institutionalized population and residents of certain remote regions. Altogether these exclusions represent approximately 3% of the target population.
Since survey participants have to get to a mobile examination center (MEC) located near their home for the physical measurements, collection sites' areas were limited to a radius of about 50 km (or up to 75 km for rural areas) with a minimum population of 10,000 persons. The sites were created using a specialized software with the aim of covering the most of the 10 provinces. The most recent version of the dwelling universe file (DUF) of the Household Survey Frame (HSF) is used to select dwellings within selected sites. Using the date of birth of household members from the most recent version of the socio-economic indicators file (SEF) of the HSF, as well as more current information from other administrative sources, dwellings are stratified and selected to ensure coverage of the survey's target age groups.
Much time and effort was devoted to reducing non-sampling errors in the survey. Quality assurance measures were applied at each stage of the data collection and processing cycle to control the quality of the data.
The effect of non-response on survey results is a major source of non-sampling error in surveys. The scope of non-response varies from partial non-response (where the respondent does not respond to one or more questions) to total non-response. In cycle 6 of the CHMS, there was little partial non-response, since once the questionnaire began, respondents tended to complete it. There was total non-response when the person selected to participate in the survey refused to do so or could not be contacted by the interviewer. Cases of total non-response were taken into account during weighting by correcting the weights of persons who responded to the survey in order to compensate for those who did not respond.
- Accessing CHMS Information Online
- List of other Canadian Health Measures Survey (CHMS) documents available
For more information or to obtain copies of the documents in this list, please contact Statistics Canada's Statistical Information Service (toll-free 1-800-263-1136; 514-283-8300; firstname.lastname@example.org).
- Canadian Health Measures Survey Bibliography 2022
Last review : July 2022.
- Canadian Health Measures Survey (CHMS). Content summary for cycles 1 to 6 (2018)