Which is the best suitable Intraclass correlation method?

[Chapi]

Hello dear SAS users,

I have a question about implementing correct ICC Intraclass correlation method on the below data. I am unable to understand if ICC1, ICC2 or ICC3 is suitable for the below data. I have looked up on the internet and though ICC2 would be suitable. But I am to double check and make sure my thinking is right. Please help me understand which id to select randomly GP_Id or Pat_Id or both. If so which is the suitable ICC method?

GP_Id	Pat_Id	No_of_Medications_prescribed
1	a	1
1	b	2
1	c	4
1	d	1
1	e	2
2	f	7
2	g	2
2	h	1
2	i	7
3	j	8
3	k	9
3	l	4
3	m	6
3	n	4

Many thanks and best regards,

Chap