Weird results - add a minus sign and the total increases!

[ppc_newbie]

The last little while I've been getting some strange result with searches.

Not a personalized search problem that I can tell?

First off being a programmer I have no problem building long boolean search strings.

Sort of like the old "search within results" concept
- So generally I'll start off with search with a 2-3 word phrase(20 million results)
red widgets
- I add a few more words to the search(2 million results)
cheap red steel widgets
- I throw in a negative keyword(500 thousand results)
cheap red steel widgets -square
- I throw in another negative keyword(5 million results)
cheap red steel widgets -square -round

So even though the last search has an additional negative keyword, the number of results increase.

[tedster]

I've been noticing that for a while. I guess the "about" before the number of pages really means "a big guess" in this case.

From what I understand, the way that Google shards their data it is not an easy task to come up with a number of pages. There have been periods of time where the "about" number was so far off it was ridiculous. This particular oddity is also pretty far out there.

[Robert Charlton]

- I throw in another negative keyword(5 million results)
cheap red steel widgets -square -round

Possibly... taking a wild stab at what the mechanism might be... this reminds me of what sometimes happened with "negative exclusion strings" that were used for a while to return original pre-filtered results during the Florida update.

Adding enough negative text strings that weren't contained in any documents would "break" the filter. Exclusion string searches took the form...

keyword -asdf -asdf

The idea was that overloading the search input would disable the extra layer of computation that was the filter on top of the "plain vanilla" search. Sometimes, it took many repetitions of -asdf to do this.

This is clearly not a very precise description of how Google worked then, and clearly Google has also changed a lot since then... but positing that returning the number of results is an add-on layer, I'm thinking out loud that something similar might be at work... ie, that adding several exclusion strings, in this case strings that are real words, could fuzz up the already approximate calculation.

[Leosghost]

Could it be as simple as just like in standard math ..if you multiply a minus number by a minus number you get a plus number ..maybe they treat the *-* ( just the minus sign between the asterisks ) as a multiplier ..so if you put two of them you are creating a positive "filter"..and multiplying the first term by it ?

[steveb]

It has to do with how Google is trying to think for searchers via misssspellings, synonyms and similiar words (patti and patty). With some exclusions Google feels compelled to throw more "extra" words into the mix.

I went from 184 results to 100,000+ a few days ago by adding -word. I wish I could remember the term now but I can't.