Offset term for proc Genmod (Poisson distribution)

[LTromp]

Hi,

I'm modelling claims frequency by using proc genmod for a GLM with Poisson distribution.  I was hoping that someone could please help me understand the "offset" term better and when it should and shouldn't be used? 

The data is at a per-policy level as in the example below, so I am unsure whether or not I should include the offset term.  Please help!

Policyholder	Gender	Age	Months insured	Total number of claims	Total amount of claims
Peter	Male	22	6	1	$10 000
Sue	Female	32	12	0	0

- Thank you

[brsinco]

Use the offset term when the sampling duration differs between at least two subjects.

Example.  If period = 6 for Peter and 12 for Sue, then your Proc GenMod code should contain offset=Period.

Hope this helps.

Brandy