Campaign VS Ad Group

[Fbase21]

What I am wanting to know involves the following procedure - I have 2 Campaigns ( A and B ) under each campaign I Have 3 ad groups (A1,A2,A3)(B1,B2,B3) - Now for my question -

Goolge measures the clicks and the impressions giving you a CTR percentage - Does google get this number by calculating the sum of all clicks in A1 through A3 , or does it do it for A1 then a seperate one for A2, and so on through B3

So if you are doing bad in ad group A1 will that affect all the A adgroups? what about the B adgroups or will it just affect A1

Also does this affect both or one of the campaigns - Or does it have any affect to the campaign at all - Will one bad ad group bring down a whole campaign?

Im curious about this - Dont see any explanations of this anywhere - Any ideas would help

thanks
Nathan

[johannes]

It's done separately.

Will one bad ad group bring down a whole campaign?

Don't think it will, unless it's really bad so it slows down the entire account.