International Youth Survey (IYS)

Detailed information for May 2005 to April 2006




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The International Youth Survey (IYS) is the Canadian portion of the International Self-Report Delinquency Study (ISRD) involving youth in Grades 7 to 9 in about 30 European countries, United States and Canada. The National Crime Prevention Centre of the federal department of Public Safety and Emergency Preparedness Canada sponsored this study. It was conducted by Statistics Canada in Toronto in the spring of 2006.

Data release - September 25, 2007


Statistics on youth delinquency based on data from police refer only to reported acts of mischief or crime. Police and court statistics represent a very small sample of misbehaving youth and contain very little information about the family or personal situation of the youth. The optimal method for understanding various types of misbehaviour in the context of relationships or bonds with parents, school, and friends is to interview youth directly.

The international study, previously conducted in 1992, analyzed and interpreted data illuminating the linkages among delinquency, age, gender and various risk factors. Selected measures of family and school-based social control were employed to further explore those relationships. The role of peers and leisure activities in the behaviour of youth was also examined.

For Canada, the value of the ISRD data has been enhanced considerably by concentrating the sample within one large urban centre where survey data could be examined together with other data, such as local census and crime data at the neighbourhood level. The city of Toronto was chosen as the most suitable urban area where Statistics Canada could conduct the survey and on which the analysis of results could focus.

By using almost the same questionnaire and data collection method as other countries, the IYS makes possible comparisons of the prevalence of types of youth misbehaviour in industrialized countries and examination of cross national variability in correlates of self-reported delinquent behaviour.

The survey is representative of each of the three grades (7 to 9) and at the grade level, of both sexes. To meet these requirements, as well as to satisfy the analytical needs of the international comparisons, about 3,200 students in 177 classes were surveyed.

The International Youth survey provides comprehensive information about delinquency and misbehaviour of young people. Data can be analyzed within the context of school policies and programs, local crime problems, and the socio-demographic make-up of local communities. This is the first such in-depth study in Canada and will help address important questions related to risk and protective factors for misbehaviour, and how schools and communities can assist high risk children to develop pro-social behaviours and positive school outcomes.

The International Youth Survey was conducted in a classroom setting and collected information on the following topics:

- Family background and family bonds;
- Friendships and spare time activities;
- Attachment to school and the neighbourhood;
- Commitment to school measured by self-reported performance and attendance;
- Personal and family traumatic experiences;
- Use of alcohol and drugs;
- The incidence of various kinds of delinquent behaviour (e.g. vandalism, theft, violence, illegal use of the internet);
- Beliefs concerning the violent behaviour of young people;
- Self-reported impulsivity, ability to control anger, penchant for risky behaviour; and
- Time devoted to paid and voluntary work.


  • Child development and behaviour
  • Children and youth
  • Crime and justice (youth)

Data sources and methodology

Target population

The target population consists of students in grades 7, 8, and 9 attending a public school belonging to the Toronto District School Board or a private school in the Toronto Metropolitan Area, at the time of collection. This represents roughly 60,000 youths. It is important to note that the Toronto Catholic School Board declined to participate in this study, so are not part of the target population and are not represented in the sample. It is estimated that students attending Catholic schools represent approximately 25% of the student population in the Toronto Metropolitan Area. Also youths who have dropped out of school or for other reasons are not enrolled in schools, are also not part of the target population. Young persons attending special schools were excluded from the target population.

The population surveyed differs very slightly from the target population. Students enrolled in small schools, in which enrolment counts for the entire grade is 10 or less, were excluded from selection. This represents less than 0.5% of students in the target population, although the proportion was higher in private schools than in the public board (3% versus less than 1%).

Instrument design

A pre-test of the questionnaire was conducted in August 2005 by a market research company. There were 34 participants recruited to represent grades 7 to 9, boys and girls, students with English or French as the language of instruction, residents in or outside the urban area of Ottawa-Gatineau, and average, above average and below average students (self-reported).

The participants were divided into six groups (boys and girls were interviewed separately). Each group session lasted approximately two hours. First, participants listened to an explanation of how the actual survey would be carried out in schools, next, they completed the paper questionnaire, and finally, they presented their comments and answered the moderator's probing questions.


This is a sample survey with a cross-sectional design.

For public schools, the Toronto District School Board provided Statistics Canada (STC) with two administrative files from which the sampling frame was created. The first file contained enrolment counts by grade for middle schools, containing grades 7 and 8. Based on the source and timeliness, the frame was considered to be of better quality than any other source available. The second file provided enrolment counts by age for high schools. Since there were no counts by grade from the high school file, age was used as a proxy for grade 9. For private schools, there was no "board" from which to obtain up-to-date, quality information, therefore STC created a frame through current available public sources and information from existing older STC frames.

It was decided to stratify by grade and two geographic areas, yielding six strata. The geographic areas were based on postal codes and were split in such a way as to ensure, as much as possible, equal student populations. Sampling was done independently in each stratum, meaning that some schools were selected more than once, for different grades.

In each stratum, schools were selected systematically with probability proportional to size, with the size measure being the school enrolment count for the grade of interest. Selection of classes was accomplished in the field by the Statistics Canada interviewer who randomly selected one class in the desired grade. This translated into a final sample of 210 classes in 176 schools being selected.

The sample was allocated to the six strata using proportional allocation. It was calculated that a sample size of 3,150 responding students was needed to yield a coefficient of variation of 16.5% or less within each estimation domain based on a minimum proportion of 12%. This sample size was then inflated to account for non-response. Based on the stratum population sizes, the number of students required in each stratum was calculated, from which the number of classes to select was estimated.

Data sources

Data collection for this reference period: 2006-04-01 to 2006-04-30

Responding to this survey is voluntary.

Data are collected directly from survey respondents.

Survey activities in schools were conducted from February to May 2006. They included mailing an introductory letter to the sampled public and private schools in Toronto, selecting the classes to participate in the survey and conducting classroom sessions during which students completed paper questionnaires. These collection activities were preceded by a lengthy school board approval process which began in September 2005.

Before the classroom session the interviewer prepared a questionnaire for each eligible child. On the cover page of the questionnaire the interviewer transcribed from the Classroom Selection Form the student's identification number composed of the school number, grade and an arbitrarily assigned student number. The student's name was not written on the questionnaire to maintain anonymity. The students' names were only written on envelopes in which questionnaires were given to students. The completed questionnaires were collected separately from the envelopes.

The classroom sessions, on average, lasted approximately 40 to 50 minutes. Teachers were asked to remain in the classroom, but not to circulate among the students to protect the privacy and confidentiality of all students taking part in the survey.

All the IYS questionnaires were data captured using a digital imaging process at Statistics Canada's head office in Ottawa. The student identification numbers were verified 100% to avoid any keying errors. The quality of the data capture task was checked by a random verification process of almost 20% of the records. The error rate was below 1%.

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

Error detection

The International Youth Survey questionnaire was designed with very few skip patterns. It was felt that skips might not be correctly followed by the younger respondents.

The survey team made the decision to edit the questionnaire using both a "top-down" and "bottom-up" approach. To accomplish this task, flows had to be determined before the edit programs could be written.

The first type of error treated were errors in the 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 does not apply.


Statistical weights were placed on each record to represent the number of sampled students that the record represents. The weighting for the International Youth Survey consisted of the following steps:

Initial sampling weight (school weight)
The first step is to calculate the initial weight for each selected unit (school-grade). For a given unit, this is equal to the inverse of the probability of selection within the stratum. This probability is proportional to the number of students at the school for the given grade. Because sampling at this level was done using probability proportional to size, some large schools needed to be placed in separate take-all strata. These schools had an initial sampling weight of 1.

The following adjustments were made to the initial weight:
- Adjustment for the non-response at the school level;
- Adjustment for the selection of a class (class weight);
- Adjustment for class non-response;
- Adjustment for student non-response;
- Post-stratification adjustment (The sampling weights for students attending public schools are adjusted to agree with the enrolment counts for certain groupings (post-strata). The enrolment counts were provided by the Toronto District School Board at the end of collection for grade-sex post-strata. For the private schools, no such counts were obtained, so the adjustment factor is simply 1).

The variance estimation method used was Bootstrap.

Quality evaluation

The prevalence of delinquent behaviours and the socio-demographic characteristics of youth who reported such behaviours were compared to other sources such as, for example, the National Longitudinal Survey of Children and Youth.

Disclosure control

Statistics Canada is prohibited by law from releasing any data that would divulge information obtained under the Statistics Act that relates to any identifiable person, business or organization without the prior knowledge or the consent in writing of that person, business or organization. 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.

The survey master file includes several variables that were removed from the IYS Public Use Microdata File (PUMF) as they could potentially identify respondents. These include the respondent's age, immigrant status, country of birth, family composition, language spoken at home, parents' employment status and repetition of grade.

An example of grouping values is the student's age which is asked at the onset of each of the misbehaviour questions (questions 49 to 71). The student's age was grouped into "Less than 10 years old" and "10 years old and older".

For certain variables that were susceptible to identifying individuals, the PUMF was treated with local suppressions, that is, some of the values in the master file may have been coded as "not stated" on the PUMF. There were 55 such suppressions affecting 12 variables.

Revisions and seasonal adjustment

This methodology does not apply to this survey.

Data accuracy

While considerable effort is made to ensure high standards throughout all stages of collection and processing, the resulting estimates are inevitably subject to a certain degree of error. These errors can be broken down into two major types: non-sampling and sampling.

Considerable time and effort were taken 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.

Sampling error occurs because population estimates are derived from a sample of the population rather than the entire population. Sampling error depends on factors such as sample size, sampling design, and the method of estimation. An important property of probability sampling is that sampling error can be computed from the sample itself by using a statistical measure called the coefficient of variation (CV). The assumption is that over repeated surveys, the relative difference between a sample estimate and the estimate that would have been obtained from an enumeration of all units in the universe would be less than twice the CV, 95 times out of 100. The range of acceptable data values yielded by a sample is called a confidence interval. Confidence intervals can be constructed around the estimate using the CV. First, we calculate the standard error by multiplying the sample estimate by the CV. The sample estimate plus or minus twice the standard error is then referred to as a 95% confidence interval.

The student response rate for the IYS 2006 was 73.2%. The overall response rate was 63.2%.

Please refer to the Microdata User Guide for detailed information.


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