smoker 1 if current smoker, 0 otherwise smkban 1 if there is a work area smoking ban, 0 otherwise age = age in years hsdrop 1 if high school dropout,...

Consider the following probit model:

pr(smoker) = Φ(smakban, age, age2, hsdrop, hsgrad, colsome, colgrad, black, other, female)

Discuss how each of the explanatory variables may affect the probability of smoking?

and how to interpret the sign of age in probit model is positive but age square is negative?