Problem 1. (2 marks) Let's assume that the following is a trip generation model for a district or a region in a city. # of peak-hour vehicle-based shopping trips per household = 0.12 +0.09 (household size) + 0.011 (annual household income in thousands of dollars) - 0.15 (employment in the household's neighborhood, in hundreds) - 0.07 (petrol/fuel price of the current week) Explain what might be the reason why the underlined coefficient of -0.15 takes a Negative value