Unchecking it means each of your ads is rotated equally, regardless of CTR. Sometimes I wonder if an aberration could make the non-converting ad get more clicks (say if it were misleading), and the better-converting ad would thus get less exposure. Hence I like to start a campaign with optimising turned off for a few days before judging the ads.
In the early stages of a campaign the optimisation could tell you which has the best CTR, but it might have the worse conversion rate.
We generally leave it off and then review CTR for poor performing creatives to delete. In the majority of cases we only have one ad showing, and A/B test through the backend, at least then your sales results are consistent with the same message.
Gets horribly complicated if you have 20 keywords, 5 ads and 3 landing pages to work out what works best...... and experience of handling campaigns counts a lot for not making mistakes.
Msg#: 3191 posted 12:52 pm on Aug 10, 2004 (gmt 0)
If you make a new campaign with content match on, I'd suggest turning ad optimization off to begin with.
The tons of impressions you can get from AdSense can muddle your ad CTRs for G/Search stats, and those are the ones for most campaigns that you want to do well. Once you understand how the search vs content CTRs play out, then turning ad optimization on can be very useful.