In addition to the single-variable terms, this regression equation includes an interaction term, that including this interaction term allows the regression model to assess a different relationship between seatbelt usage and obesity for states that have a seatbelt law and for those states without such law. For states without a seatbelt law (i.e.x is equal to one), this change is estimated by similarly , the impact of a seatbelt law on the fractional seatbelt usage rate in a state is estimated as , and hence, this impact depends on the obesity rate in the state.