Any mathletes out there?

OK..its Aussie stats..but hey, should be close.

Attrition rate

The estimated proportion of motor vehicles taken off the register since the previous MVC (Motor Vehicles Constructed). The attrition rate is also referred to as the motor vehicle retirement or scrappage rate. The number of registration lapses is calculated by adding the total registrations at the earlier MVC to the number of new motor vehicle sales between the MVCs, and subtracting the total registrations at the later MVC. The attrition rate measures the number of registration lapses as a percentage of the total potential vehicle fleet, where the potential vehicle fleet is the number of registrations at the first MVC date plus the number of new motor vehicle sales between the two MVCs. To calculate the annualised attrition rate as a percentage apply the following formula:

Formula wont paste, but its here:-

http://www.abs.gov.au/ausstats/abs@....011&num=&view=

where T1 is the number of registrations at the first time point, N1 is the number of new sales between the first and second time points, T2 is the number of registrations at the second time point and M is the number of months between the two time points.


Have at it.....

Jo