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CHIS Data Quality

CHIS Methods to Accurately Represent California's Diverse Population

CHIS employs a number of strategies to produce high quality data that accurately represent California's diverse population. These strategies include:

Language inclusivity - CHIS is conducted in English, Spanish, Chinese (Cantonese and Mandarin), Korean, and Vietnamese. Based on analyses of Census 2000 data for California, language selection was designed to maximize the inclusion of linguistically isolated households.

Advance letter - a letter is mailed to most sampled households before an attempt is made to contact the household by telephone. The letter is printed in all 5 CHIS administration languages, alerts the household that they will soon receive a phone call, and helps to differentiate CHIS from telemarketers.

Incentives - since CHIS 2005, the advance letter has included a $2 bill to encourage households to participate. This modest incentive does not compensate participants for their time, but helps to draw attention to the survey, emphasize its importance, and encourage participation.

Toll-free line - a toll-free line is available to respondents during the entire CHIS field period. Potential respondents can call to have their questions answered, schedule an interview, be assured of the legitimacy of the survey, etc. The toll-free number is printed on the advance letter and may also be provided by an interviewer.

Respondent web site - a special website is maintained during the field period that includes a FAQ feature so that respondents can learn more about the survey. The website address is printed on the advance letter and is often provided to potential respondents by interviewers.

Maximum call attempts - each sampled telephone number is dialed at least 14 times, on different days (weekdays and weekends) and at different times of the day in order to make contact with a household. If the household is initially reached at an inconvenient time, call-back appointments are made to accommodate the respondent's schedule. Messages are also left on answering machines to help differentiate CHIS from telemarketers and encourage participation in the survey.

Well-trained, high-quality interviews - CHIS interviewers receive a minimum of 18 hours of training and are constantly monitored and supervised to ensure high-quality data collection. CHIS data collection is conducted by Westat, Inc., an employee-owned survey research organization with a national reputation for quality.

Certificate of Confidentiality - CHIS obtains this certificate from the National Institutes of Health. The certificate protects the confidentiality of CHIS respondents and the information they provide from forced disclosure, such as a court subpoena. CHIS steadfastly protects the confidentiality of all participants. CHIS protocols for participant recruitment, data collection, and the dissemination and storage of data is governed by the UCLA Office for the Protection of Research Subjects, the California Committee for the Protection of Human Subjects, and the federal Office of Management and Budget.