What assumptions must hold for ols to give an unbiased

Question

Consider the regression model of:

murderrate_t = β₀ + β₁ policebudget_t + ?_t

where murderrate_t is the annual murder rate in Fresno in year t, policebudget_t is the annual police budget in Bakersfield. The data set available has one observation for each of the last 36 years.

(a) What assumptions must hold for OLS to give an unbiased estimate of the β₁ the structural effect of increasing the police budget on the murder rate?

(b) Which of these assumptions is most likely violated if policebudget_t, depends on murderratet-1?

(c) What assumptions must hold for OLS to give a consistent estimate of the β₁, the structural effect of increasing the police budget on the murder rate?

(d) Which of these assumptions is most likely violated if policebudget_t, depends on murderrate_t-1?