Example: if you were selling pearl jewelry, it would be foolish to bid for broad match on "pearl" without some negatives, because many searches that include the word "pearl" are about something completely different than what you're selling.
Pearl Harbor, Pearl Bailey, Pearl Jam, Pearl drums, Pearl S. Buck, and so on... there's no point showing your ad to the wrong eyeballs just because there's some overlap in vocabulary.
A few simple negatives could save huge numbers of wasted impressions:
-harbor
-jam
-drums
-bailey
-buck
Invest some thought to identify searches where your ads ought not to appear, and enter some select negatives to block them.
Pearl of wisdom: Reducing off-target impressions is one of the easiest ways to improve your clickthrough percentages.
adgroup1:
[pearl]
adgroup2:
"pearl"
adgroup3:
pearl
adgroup3 will have dismal conversions and the max cpc will drop accordingly. adgroup1 is straightforward and adgroup2 will be somewhere in-between. The advantage of this is absolutely no time spent on negative keywords.
As for all the juicy multi-word keywords you miss out on in adgroup3 because your max cpc is so low, they can be added like this:
adgroup4:
[pearl jewelry]
adgroup5:
"pearl jewelry"
adgroup6:
pearl jewelry
The advantage of this is absolutely no time spent on negative keywords.
How much time are you thinking here?
You wouldn't have to change a thing about how you've structured your ad groups.
If you spent even ten minutes with a good keyword research tool you'd have no trouble spotting some candidates for blocking, and it wouldn't take long to add them as negative keywords at the campaign level. I guarantee that those few minutes would have some of the best ROI of anything you did all year.
You could do a lot more than that, of course ... some people have hundreds or even thousands of negative keywords ... but identifying even the top half-dozen negative keywords would improve the profitability of a campaign if broad matching is involved.
Can you tell me why the negative keyword approach is better than the one I've described? If you isolate broad matches in their own ad groups and add new keywords in new ad groups based on the good stuff broad match finds, you've avoided paying for the bad matches without the risk of negative keyword false positives and without the negative keyword management time.
Just like a broad match keyword can bring in a bunch of crap, a negative match keyword can keep relevant stuff out, especially if the product line is evolving.
Can you tell me why the negative keyword approach is better than the one I've described?
Using negative keywords is not something different from what you've described, it's a technique to fine-tune what you've described, to further tighten your targeting.
you've avoided paying for the bad matches
No, if you have bad matches, they cost you, period. If you have ads appearing in off-target searches simply because of vocabulary overlap, you lose in two ways:
(1) Your CTR will be lower, and thus your Quality Score. That results in less visibility for the same ad spend.
(2) Clicks that you do get from off-target impressions will convert poorly.
a negative match keyword can keep relevant stuff out
Only if you've chosen your negatives badly.