TASK:

Model the frequency of crashes.


This data set consists of drivers involved in a crash in 2004 in New South
Wales, Australia, in which the involvement of blood alcohol concentration (BAC) was known. 

Drivers with unknown age, age less than
17 years, or unknown BAC are omitted, leaving 58890
cases.

Variables:
agecat		driver's age, coded as
		1 = 17-20
		2 = 21-25
		3 = 26-29
		10 = 30-39 (4 coded as 10 to be base level) 
		5 = 40-49
		6 = 50-59
		7 = 60+

bac		1 = legal
		2 = .020-.049 g/100mL
		3 = .050-.079 g/100mL
		4 = .080-.149 g/100mL
		5 = >= .150 g/100mL

sex		driver's sex: M, F

degree		degree of crash, coded as
		1 = non-casualty
		2 = injury
		3 = fatal

number		frequency of crashes