In-School

In-School Sampling Frame

The clustered sampling design of Add Health is school-based for two reasons:

• This is the best way to screen for respondents of interest.
• With the school as a center, it is relatively easy to access the majority of respondents' peers, whose influences are fundamental to the study's hypotheses.

The primary sampling frame for Add Health is a database collected by Quality Education Data, Inc. Systematic sampling methods and implicit stratification ensure that the 80 high schools selected are representative of US schools with respect to region of country, urbanicity, size, type, and ethnicity. Eligible high schools included an 11th grade and enrolled more than 30 students. More than 70 percent of the originally sampled high schools participated. Each school that declined to participate was replaced by a school within the stratum.

Participating high schools helped to identify feeder schools—that is, schools that included a 7th grade and sent at least five graduates to that high school. From among the feeder schools, one was selected with probability proportional to the number of students it contributed to the high school. If the feeder school declined to participate, a replacement was selected. The recruitment effort resulted in a pair of schools in each of 80 communities (Some high schools spanned grades 7 through 12; for those, a separate feeder school was not recruited.) There are 132 schools in the core study.

In-School Questionnaire

The In-School Questionnaire, a self-administered instrument formatted for optical scanning, was administered to more than 90,000 students in grades 7 through 12 in a 45- to 60-minute class period between September 1994 and April 1995. There was no "make-up" day for absent students. Parents were informed in advance of the date of the questionnaire and could direct that their children not participate.

The questionnaire included topics such as these:

• social and demographic characteristics of respondents (of interest both as data and as selection criteria for in-home special samples)
• education and occupation of parents
• household structure
• risk behaviors
• expectations for the future
• self-esteem
• health status
• friendships
• school-year extracurricular activities

Each participating school provided a student roster. Project staff assigned an identification number to each name and provided copies of the rosters to students for identifying their friends as they filled out the questionnaire. Rosters were collected at the end of the class period and destroyed.

School Administrator Questionnaires

Administrators from participating schools completed self-administered questionnaires dealing with school policies and procedures, teacher characteristics, health-service provision or referral, and student body characteristics.

School Administrator Telephone Interviews

In the spring of 1996 school administrators were contacted by telephone and asked to update information from the first year and add information about specific dress codes and security procedures on their campuses.