Ontario Child Health Study (OCHS)

Detailed information for 2000-2001 (second follow-up)





Record number:


The survey was conducted by Statistics Canada on behalf of the Canadian Centre for Studies of Children at Risk at McMaster University in Hamilton, Ontario. The Ontario Child Health Study (OCHS) is a long-term survey designed to evaluate the impact of early childhood experiences and development on later adult health, quality of life and functioning.

Please note that no public use microdata file was produced by Statistics Canada and data will not be made available through the Data Liberation Initiative (DLI). For information related to the analysis of the data from this study, contact Yvonne Racine (905-521-2100 ext. 74345; fax: 905-521-4970; raciney@mcmaster.ca), McMaster University.

Data release - January 9, 2004


Statistics Canada, in conjunction with McMaster University, originally collected information on a representative group of 3,294 Ontario children living in 1,869 families. This study, funded by the government of Ontario, was one of the first large-scale assessments of the physical and emotional health of Ontario's children. The survey was first conducted in 1983 and the children selected were between 4 and 16 years of age. The main purpose of the study was to look at the overall health of the children in Ontario, to see how their health needs were being met and to identify factors that helped or hindered their development.

A follow-up study with these same children was conducted in 1987 when these respondents were between 8 and 20 years of age. The study provided important information about which health aspects of these children had changed or remained the same over the previous four years.

Beginning in November 2000, Statistics Canada conducted a second follow-up survey with the original children in this study. This survey looked at the possible influences of early experiences on important life transitions, such as joining the workforce, entering into a relationship with someone or becoming a parent. All the original respondents, now between the ages of 21 and 33 years, were eligible to participate in this collection.

Please note that no public use microdata file was produced by Statistics Canada and data will not be made available through the Data Liberation Initiative (DLI).


  • Children and youth
  • Health and well-being (youth)

Data sources and methodology

Target population

The target population for the original 1983 OCHS included all children born from January 1, 1966 through January 1, 1979, whose usual place of residence was in a household located in the province of Ontario. The survey excluded children living on Indian reserves, those in collective dwellings such as institutions, and those living in dwellings constructed after June 1, 1981 (Census day); this excluded population represented 3.3% of the target population. For the 1987 and 2000 follow-up studies, the original longitudinal respondents were located and interviewed.

Instrument design

For the second follow-up in 2000, three separate field tests were carried out beginning in August and September 1999, on a convenience sample found by going door-to-door in Burlington and Brampton Ontario. These field tests were used to test the content of the survey. A pilot test, to test survey procedures was conducted in September 2000.


This is a sample survey with a longitudinal design.

The sample for the 1983 OCHS was selected from a frame consisting of all dwellings identified in the 1981 Census of Population. A stratified, clustered, random sample of dwellings was selected from this frame. The sample was stratified into four health regions; each region was then divided into three strata based on the population density (large urban, small urban or rural).

A total of 2,623 households were selected for the 1983 OCHS. Of these, 78.2% were found to be eligible for the survey (i.e. a child in the target population lived in the household); 91.1% of these households agreed to participate in the study. All eligible children living in a responding household were selected as longitudinal respondents for the study. This resulted in responses from 3,294 Ontario children living in 1,869 households.

All children and families who participated in the original OCHS were eligible for follow-up in 1987. Among the 1,869 households, 1,660 (88.8%) were traced and 1,546 (82.7%) agreed to participate.

For the follow-up study in 2000, Statistics Canada attempted to locate the original longitudinal respondents from the 1983 sample. Tracing was done using the addresses collected in 1983 and 1987, contacting the parents or other relatives (based on information given in previous collections), and using other methods (public use files, etc.). In total, 2,896 of the 3,294 longitudinal respondents were located.

Data sources

Responding to this survey is voluntary.

Data are collected directly from survey respondents.

Data collection for the Ontario Child Health Study (OCHS) was carried out between November 2000 and November 2001 by a staff of trained Statistics Canada interviewers.

Data collection was done using a combination of telephone and personal interviews. There were two phases to the interview. Phase one consisted of a brief telephone interview to confirm that the correct respondent had been found, outline the study objectives, and administer the OCHS 1 - Demographic Questionnaire with relationship grid. Phase two consisted of a personal interview to collect the OCHS 2 - Respondent Questionnaire, OCHS 3 - Respondent Self-complete Questionnaire, OCHS 4 - Partner Self-complete Questionnaire (if the respondent had a spouse/partner), and OCHS 5 - Ages and Stages Questionnaire (for a selected child between the age of 3 and 71 months if applicable). For longitudinal respondents who were living outside Canada, a telephone interview was conducted using the OCHS 6 -- Out-migrant Questionnaire (a short version of the OCHS 2 questionnaire).

The interview took approximately 1¿ hours, depending on whether or not the respondent had a partner and whether or not the selected child was eligible for the OCHS 5 questionnaire.

In order to minimize non-response, the decision was taken that if a longitudinal respondent was refusing to do the full survey, but would be willing to do a shorter interview, the OCHS 6 questionnaire was administered in these circumstances.

Capture of survey data was accomplished using the data capture facilities located at Statistics Canada's head office. During this process any document containing at least one interviewer-completed item was captured.

View the Questionnaire(s) and reporting guide(s).

Error detection

The first stage of survey processing undertaken at head office was the replacement of any "out-of-range" values on the data file with blanks. This process was designed to make further editing easier.

The first type of error treated was errors in questionnaire flow, where questions which did not apply to the respondent (and should therefore not have been answered) were found to contain answers. In this case a computer edit automatically eliminated superfluous data by following the flow of the questionnaire implied by answers to previous, and in some cases, subsequent questions.

The second type of error treated involved a lack of information in questions which should have been answered. For this type of error, a non-response or "not-stated" code was assigned to the item.


This methodology type does not apply to this statistical program.


For the OCHS, each respondent represents people who were in the target population for the original 1983 survey -- that is, children aged 4 to 16 living in Ontario in 1983. A base weight was calculated for these respondents for the 1983 data file. For the 2000 data file, the 1983 base weight was used as a starting point. Adjustments were then made for non-response (traced, but did not respond) and for non-traced (unable to locate the person) based on characteristics available from the 1983 survey data. Finally, the weights were benchmarked to six age-sex groupings within each of four sub-provincial regions, using the age, sex and region information from 1983.

Quality evaluation

Considerable time and effort was made to reduce non sampling errors in the survey. Quality assurance measures were implemented at each step of the data collection and processing cycle to monitor the quality of the data. These measures include the use of highly skilled interviewers, extensive training of interviewers with respect to the survey procedures and questionnaire, observation of interviewers to detect problems of questionnaire design or misunderstanding of instructions, procedures to ensure that data capture errors were minimized and coding and edit quality checks to verify the processing logic.

Disclosure control

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.

No public use microdata file will be produced by Statistics Canada and data will not be made available through the Data Liberation Initiative (DLI).

Revisions and seasonal adjustment

This methodology type does not apply to this statistical program.

Data accuracy

The overall response rate for the 2000 OCHS collection was 71.5% of the original 3,294 longitudinal respondents.


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