The paper proposes a stochastic frontier model with random coefficients to separate technical inefficiency from technological differences across firms, and free the frontier model from the restrictive assumption that all firms must share exactly the same technological possibilities.

The paper proposes a stochastic frontier model with random coefficients to separate technical inefficiency from technological differences across firms, and free the frontier model from the restrictive assumption that all firms must share exactly the same technological possibilities.

A lifetime portfolio of risky and risk-free sexual activities is conceptually constructed in this paper. People's time allocation between risky and risk-free sexual activities affects, and is affected by, the prevalence of AIDS. A small satisfaction differential between risky sex and risk-free...