  We investigate a class of binary choice models with social interactions. We
propose a unifying perspective that integrates economic models using a utility
function and psychological models using an impact function. A general approach
for analyzing the equilibrium structure of these models within mean-field
approximation is developed. It is shown that within a mean-field approach both
the utility function and the impact function models are equivalent to threshold
models. The interplay between heterogeneity and randomness in model formulation
is discussed. A general framework is applied in a number of examples leading to
some well-known models but also showing the possibility of more complex
dynamics related to multiple equilibria. Our synthesis can provide a basis for
many practical applications extending the scope of binary choice models.
