Precision across race, age and gender of a HIV risk screen for adolescents and young adults.

Identification of adolescents and young adults at high risk for HIV infection in South Africa is a key component of current and future prevention efforts. A 5-item measure was developed in the current study with acceptable levels of reliability and validity, and all items discriminating sufficiently between respondents at different levels of risk. However, both uniform and non-uniform differential item functioning (DIF) were revealed as problems: items performed differently by age, race, and gender groups. Consequently age-, race-, and gender-specific percentile-based norms were developed. Implications for policy and practice are discussed.