Online advertising stats

I’m sure I’m not the first to notice, but I realised today that it is very difficult to find stats on the actual effectiveness of online advertising.

There’s lots of stats and announcements about ad spend, but very little on cost-per-click.

I’m not a fan of online advertising as it is (even though we’ve been testing it for campaigns and will probably do some more testing for specific fundraising appeals), and this lack of information just makes me all the more dubious about its effectiveness.

Update: seems I’m not alone.